"dis" --- Python bytecode的反組譯器
***********************************

**原始碼：**Lib/dis.py

======================================================================

"dis" 模組支援反組譯分析 CPython *bytecode*。CPython bytecode 作為輸入
的模組被定義於 "Include/opcode.h" 並且被編譯器和直譯器所使用。

**CPython implementation detail:** Bytecode is an implementation
detail of the CPython interpreter.  No guarantees are made that
bytecode will not be added, removed, or changed between versions of
Python.  Use of this module should not be considered to work across
Python VMs or Python releases.

3.6 版更變: Use 2 bytes for each instruction. Previously the number of
bytes varied by instruction.

Example: Given the function "myfunc()":

   def myfunc(alist):
       return len(alist)

the following command can be used to display the disassembly of
"myfunc()":

   >>> dis.dis(myfunc)
     2           0 LOAD_GLOBAL              0 (len)
                 2 LOAD_FAST                0 (alist)
                 4 CALL_FUNCTION            1
                 6 RETURN_VALUE

(The "2" is a line number).


Bytecode analysis
=================

3.4 版新加入.

The bytecode analysis API allows pieces of Python code to be wrapped
in a "Bytecode" object that provides easy access to details of the
compiled code.

class dis.Bytecode(x, *, first_line=None, current_offset=None)

   Analyse the bytecode corresponding to a function, generator,
   asynchronous generator, coroutine, method, string of source code,
   or a code object (as returned by "compile()").

   This is a convenience wrapper around many of the functions listed
   below, most notably "get_instructions()", as iterating over a
   "Bytecode" instance yields the bytecode operations as "Instruction"
   instances.

   If *first_line* is not "None", it indicates the line number that
   should be reported for the first source line in the disassembled
   code.  Otherwise, the source line information (if any) is taken
   directly from the disassembled code object.

   If *current_offset* is not "None", it refers to an instruction
   offset in the disassembled code. Setting this means "dis()" will
   display a "current instruction" marker against the specified
   opcode.

   classmethod from_traceback(tb)

      Construct a "Bytecode" instance from the given traceback,
      setting *current_offset* to the instruction responsible for the
      exception.

   codeobj

      The compiled code object.

   first_line

      The first source line of the code object (if available)

   dis()

      Return a formatted view of the bytecode operations (the same as
      printed by "dis.dis()", but returned as a multi-line string).

   info()

      Return a formatted multi-line string with detailed information
      about the code object, like "code_info()".

   3.7 版更變: This can now handle coroutine and asynchronous
   generator objects.

Example:

   >>> bytecode = dis.Bytecode(myfunc)
   >>> for instr in bytecode:
   ...     print(instr.opname)
   ...
   LOAD_GLOBAL
   LOAD_FAST
   CALL_FUNCTION
   RETURN_VALUE


Analysis functions
==================

The "dis" module also defines the following analysis functions that
convert the input directly to the desired output. They can be useful
if only a single operation is being performed, so the intermediate
analysis object isn't useful:

dis.code_info(x)

   Return a formatted multi-line string with detailed code object
   information for the supplied function, generator, asynchronous
   generator, coroutine, method, source code string or code object.

   Note that the exact contents of code info strings are highly
   implementation dependent and they may change arbitrarily across
   Python VMs or Python releases.

   3.2 版新加入.

   3.7 版更變: This can now handle coroutine and asynchronous
   generator objects.

dis.show_code(x, *, file=None)

   Print detailed code object information for the supplied function,
   method, source code string or code object to *file* (or
   "sys.stdout" if *file* is not specified).

   This is a convenient shorthand for "print(code_info(x),
   file=file)", intended for interactive exploration at the
   interpreter prompt.

   3.2 版新加入.

   3.4 版更變: Added *file* parameter.

dis.dis(x=None, *, file=None, depth=None)

   Disassemble the *x* object.  *x* can denote either a module, a
   class, a method, a function, a generator, an asynchronous
   generator, a coroutine, a code object, a string of source code or a
   byte sequence of raw bytecode. For a module, it disassembles all
   functions. For a class, it disassembles all methods (including
   class and static methods). For a code object or sequence of raw
   bytecode, it prints one line per bytecode instruction. It also
   recursively disassembles nested code objects (the code of
   comprehensions, generator expressions and nested functions, and the
   code used for building nested classes). Strings are first compiled
   to code objects with the "compile()" built-in function before being
   disassembled.  If no object is provided, this function disassembles
   the last traceback.

   The disassembly is written as text to the supplied *file* argument
   if provided and to "sys.stdout" otherwise.

   The maximal depth of recursion is limited by *depth* unless it is
   "None". "depth=0" means no recursion.

   3.4 版更變: Added *file* parameter.

   3.7 版更變: Implemented recursive disassembling and added *depth*
   parameter.

   3.7 版更變: This can now handle coroutine and asynchronous
   generator objects.

dis.distb(tb=None, *, file=None)

   Disassemble the top-of-stack function of a traceback, using the
   last traceback if none was passed.  The instruction causing the
   exception is indicated.

   The disassembly is written as text to the supplied *file* argument
   if provided and to "sys.stdout" otherwise.

   3.4 版更變: Added *file* parameter.

dis.disassemble(code, lasti=-1, *, file=None)
dis.disco(code, lasti=-1, *, file=None)

   Disassemble a code object, indicating the last instruction if
   *lasti* was provided.  The output is divided in the following
   columns:

   1. the line number, for the first instruction of each line

   2. the current instruction, indicated as "-->",

   3. a labelled instruction, indicated with ">>",

   4. the address of the instruction,

   5. the operation code name,

   6. operation parameters, and

   7. interpretation of the parameters in parentheses.

   The parameter interpretation recognizes local and global variable
   names, constant values, branch targets, and compare operators.

   The disassembly is written as text to the supplied *file* argument
   if provided and to "sys.stdout" otherwise.

   3.4 版更變: Added *file* parameter.

dis.get_instructions(x, *, first_line=None)

   Return an iterator over the instructions in the supplied function,
   method, source code string or code object.

   The iterator generates a series of "Instruction" named tuples
   giving the details of each operation in the supplied code.

   If *first_line* is not "None", it indicates the line number that
   should be reported for the first source line in the disassembled
   code.  Otherwise, the source line information (if any) is taken
   directly from the disassembled code object.

   3.4 版新加入.

dis.findlinestarts(code)

   This generator function uses the "co_firstlineno" and "co_lnotab"
   attributes of the code object *code* to find the offsets which are
   starts of lines in the source code.  They are generated as
   "(offset, lineno)" pairs. See Objects/lnotab_notes.txt for the
   "co_lnotab" format and how to decode it.

   3.6 版更變: Line numbers can be decreasing. Before, they were
   always increasing.

dis.findlabels(code)

   Detect all offsets in the code object *code* which are jump
   targets, and return a list of these offsets.

dis.stack_effect(opcode, oparg=None, *, jump=None)

   Compute the stack effect of *opcode* with argument *oparg*.

   If the code has a jump target and *jump* is "True",
   "stack_effect()" will return the stack effect of jumping.  If
   *jump* is "False", it will return the stack effect of not jumping.
   And if *jump* is "None" (default), it will return the maximal stack
   effect of both cases.

   3.4 版新加入.

   3.8 版更變: Added *jump* parameter.


Python Bytecode Instructions
============================

The "get_instructions()" function and "Bytecode" class provide details
of bytecode instructions as "Instruction" instances:

class dis.Instruction

   Details for a bytecode operation

   opcode

      numeric code for operation, corresponding to the opcode values
      listed below and the bytecode values in the Opcode collections.

   opname

      human readable name for operation

   arg

      numeric argument to operation (if any), otherwise "None"

   argval

      resolved arg value (if known), otherwise same as arg

   argrepr

      human readable description of operation argument

   offset

      start index of operation within bytecode sequence

   starts_line

      line started by this opcode (if any), otherwise "None"

   is_jump_target

      "True" if other code jumps to here, otherwise "False"

   3.4 版新加入.

The Python compiler currently generates the following bytecode
instructions.

**General instructions**

NOP

   Do nothing code.  Used as a placeholder by the bytecode optimizer.

POP_TOP

   Removes the top-of-stack (TOS) item.

ROT_TWO

   Swaps the two top-most stack items.

ROT_THREE

   Lifts second and third stack item one position up, moves top down
   to position three.

ROT_FOUR

   Lifts second, third and forth stack items one position up, moves
   top down to position four.

   3.8 版新加入.

DUP_TOP

   Duplicates the reference on top of the stack.

   3.2 版新加入.

DUP_TOP_TWO

   Duplicates the two references on top of the stack, leaving them in
   the same order.

   3.2 版新加入.

**Unary operations**

Unary operations take the top of the stack, apply the operation, and
push the result back on the stack.

UNARY_POSITIVE

   Implements "TOS = +TOS".

UNARY_NEGATIVE

   Implements "TOS = -TOS".

UNARY_NOT

   Implements "TOS = not TOS".

UNARY_INVERT

   Implements "TOS = ~TOS".

GET_ITER

   Implements "TOS = iter(TOS)".

GET_YIELD_FROM_ITER

   If "TOS" is a *generator iterator* or *coroutine* object it is left
   as is.  Otherwise, implements "TOS = iter(TOS)".

   3.5 版新加入.

**Binary operations**

Binary operations remove the top of the stack (TOS) and the second
top-most stack item (TOS1) from the stack.  They perform the
operation, and put the result back on the stack.

BINARY_POWER

   Implements "TOS = TOS1 ** TOS".

BINARY_MULTIPLY

   Implements "TOS = TOS1 * TOS".

BINARY_MATRIX_MULTIPLY

   Implements "TOS = TOS1 @ TOS".

   3.5 版新加入.

BINARY_FLOOR_DIVIDE

   Implements "TOS = TOS1 // TOS".

BINARY_TRUE_DIVIDE

   Implements "TOS = TOS1 / TOS".

BINARY_MODULO

   Implements "TOS = TOS1 % TOS".

BINARY_ADD

   Implements "TOS = TOS1 + TOS".

BINARY_SUBTRACT

   Implements "TOS = TOS1 - TOS".

BINARY_SUBSCR

   Implements "TOS = TOS1[TOS]".

BINARY_LSHIFT

   Implements "TOS = TOS1 << TOS".

BINARY_RSHIFT

   Implements "TOS = TOS1 >> TOS".

BINARY_AND

   Implements "TOS = TOS1 & TOS".

BINARY_XOR

   Implements "TOS = TOS1 ^ TOS".

BINARY_OR

   Implements "TOS = TOS1 | TOS".

**In-place operations**

In-place operations are like binary operations, in that they remove
TOS and TOS1, and push the result back on the stack, but the operation
is done in-place when TOS1 supports it, and the resulting TOS may be
(but does not have to be) the original TOS1.

INPLACE_POWER

   Implements in-place "TOS = TOS1 ** TOS".

INPLACE_MULTIPLY

   Implements in-place "TOS = TOS1 * TOS".

INPLACE_MATRIX_MULTIPLY

   Implements in-place "TOS = TOS1 @ TOS".

   3.5 版新加入.

INPLACE_FLOOR_DIVIDE

   Implements in-place "TOS = TOS1 // TOS".

INPLACE_TRUE_DIVIDE

   Implements in-place "TOS = TOS1 / TOS".

INPLACE_MODULO

   Implements in-place "TOS = TOS1 % TOS".

INPLACE_ADD

   Implements in-place "TOS = TOS1 + TOS".

INPLACE_SUBTRACT

   Implements in-place "TOS = TOS1 - TOS".

INPLACE_LSHIFT

   Implements in-place "TOS = TOS1 << TOS".

INPLACE_RSHIFT

   Implements in-place "TOS = TOS1 >> TOS".

INPLACE_AND

   Implements in-place "TOS = TOS1 & TOS".

INPLACE_XOR

   Implements in-place "TOS = TOS1 ^ TOS".

INPLACE_OR

   Implements in-place "TOS = TOS1 | TOS".

STORE_SUBSCR

   Implements "TOS1[TOS] = TOS2".

DELETE_SUBSCR

   Implements "del TOS1[TOS]".

**Coroutine opcodes**

GET_AWAITABLE

   Implements "TOS = get_awaitable(TOS)", where "get_awaitable(o)"
   returns "o" if "o" is a coroutine object or a generator object with
   the CO_ITERABLE_COROUTINE flag, or resolves "o.__await__".

   3.5 版新加入.

GET_AITER

   Implements "TOS = TOS.__aiter__()".

   3.5 版新加入.

   3.7 版更變: Returning awaitable objects from "__aiter__" is no
   longer supported.

GET_ANEXT

   Implements "PUSH(get_awaitable(TOS.__anext__()))".  See
   "GET_AWAITABLE" for details about "get_awaitable"

   3.5 版新加入.

END_ASYNC_FOR

   Terminates an "async for" loop.  Handles an exception raised when
   awaiting a next item.  If TOS is "StopAsyncIteration" pop 7 values
   from the stack and restore the exception state using the second
   three of them.  Otherwise re-raise the exception using the three
   values from the stack.  An exception handler block is removed from
   the block stack.

   3.8 版新加入.

BEFORE_ASYNC_WITH

   Resolves "__aenter__" and "__aexit__" from the object on top of the
   stack.  Pushes "__aexit__" and result of "__aenter__()" to the
   stack.

   3.5 版新加入.

SETUP_ASYNC_WITH

   Creates a new frame object.

   3.5 版新加入.

**Miscellaneous opcodes**

PRINT_EXPR

   Implements the expression statement for the interactive mode.  TOS
   is removed from the stack and printed.  In non-interactive mode, an
   expression statement is terminated with "POP_TOP".

SET_ADD(i)

   Calls "set.add(TOS1[-i], TOS)".  Used to implement set
   comprehensions.

LIST_APPEND(i)

   Calls "list.append(TOS[-i], TOS)".  Used to implement list
   comprehensions.

MAP_ADD(i)

   Calls "dict.__setitem__(TOS1[-i], TOS1, TOS)".  Used to implement
   dict comprehensions.

   3.1 版新加入.

   3.8 版更變: Map value is TOS and map key is TOS1. Before, those
   were reversed.

For all of the "SET_ADD", "LIST_APPEND" and "MAP_ADD" instructions,
while the added value or key/value pair is popped off, the container
object remains on the stack so that it is available for further
iterations of the loop.

RETURN_VALUE

   Returns with TOS to the caller of the function.

YIELD_VALUE

   Pops TOS and yields it from a *generator*.

YIELD_FROM

   Pops TOS and delegates to it as a subiterator from a *generator*.

   3.3 版新加入.

SETUP_ANNOTATIONS

   Checks whether "__annotations__" is defined in "locals()", if not
   it is set up to an empty "dict". This opcode is only emitted if a
   class or module body contains *variable annotations* statically.

   3.6 版新加入.

IMPORT_STAR

   Loads all symbols not starting with "'_'" directly from the module
   TOS to the local namespace. The module is popped after loading all
   names. This opcode implements "from module import *".

POP_BLOCK

   Removes one block from the block stack.  Per frame, there is a
   stack of blocks, denoting "try" statements, and such.

POP_EXCEPT

   Removes one block from the block stack. The popped block must be an
   exception handler block, as implicitly created when entering an
   except handler.  In addition to popping extraneous values from the
   frame stack, the last three popped values are used to restore the
   exception state.

POP_FINALLY(preserve_tos)

   Cleans up the value stack and the block stack.  If *preserve_tos*
   is not "0" TOS first is popped from the stack and pushed on the
   stack after performing other stack operations:

   * If TOS is "NULL" or an integer (pushed by "BEGIN_FINALLY" or
     "CALL_FINALLY") it is popped from the stack.

   * If TOS is an exception type (pushed when an exception has been
     raised) 6 values are popped from the stack, the last three popped
     values are used to restore the exception state.  An exception
     handler block is removed from the block stack.

   It is similar to "END_FINALLY", but doesn't change the bytecode
   counter nor raise an exception.  Used for implementing "break",
   "continue" and "return" in the "finally" block.

   3.8 版新加入.

BEGIN_FINALLY

   Pushes "NULL" onto the stack for using it in "END_FINALLY",
   "POP_FINALLY", "WITH_CLEANUP_START" and "WITH_CLEANUP_FINISH".
   Starts the "finally" block.

   3.8 版新加入.

END_FINALLY

   Terminates a "finally" clause.  The interpreter recalls whether the
   exception has to be re-raised or execution has to be continued
   depending on the value of TOS.

   * If TOS is "NULL" (pushed by "BEGIN_FINALLY") continue from the
     next instruction. TOS is popped.

   * If TOS is an integer (pushed by "CALL_FINALLY"), sets the
     bytecode counter to TOS.  TOS is popped.

   * If TOS is an exception type (pushed when an exception has been
     raised) 6 values are popped from the stack, the first three
     popped values are used to re-raise the exception and the last
     three popped values are used to restore the exception state.  An
     exception handler block is removed from the block stack.

LOAD_BUILD_CLASS

   Pushes "builtins.__build_class__()" onto the stack.  It is later
   called by "CALL_FUNCTION" to construct a class.

SETUP_WITH(delta)

   This opcode performs several operations before a with block starts.
   First, it loads "__exit__()" from the context manager and pushes it
   onto the stack for later use by "WITH_CLEANUP_START".  Then,
   "__enter__()" is called, and a finally block pointing to *delta* is
   pushed.  Finally, the result of calling the "__enter__()" method is
   pushed onto the stack.  The next opcode will either ignore it
   ("POP_TOP"), or store it in (a) variable(s) ("STORE_FAST",
   "STORE_NAME", or "UNPACK_SEQUENCE").

   3.2 版新加入.

WITH_CLEANUP_START

   Starts cleaning up the stack when a "with" statement block exits.

   At the top of the stack are either "NULL" (pushed by
   "BEGIN_FINALLY") or 6 values pushed if an exception has been raised
   in the with block.  Below is the context manager's "__exit__()" or
   "__aexit__()" bound method.

   If TOS is "NULL", calls "SECOND(None, None, None)", removes the
   function from the stack, leaving TOS, and pushes "None" to the
   stack.  Otherwise calls "SEVENTH(TOP, SECOND, THIRD)", shifts the
   bottom 3 values of the stack down, replaces the empty spot with
   "NULL" and pushes TOS.  Finally pushes the result of the call.

WITH_CLEANUP_FINISH

   Finishes cleaning up the stack when a "with" statement block exits.

   TOS is result of "__exit__()" or "__aexit__()" function call pushed
   by "WITH_CLEANUP_START".  SECOND is "None" or an exception type
   (pushed when an exception has been raised).

   Pops two values from the stack.  If SECOND is not None and TOS is
   true unwinds the EXCEPT_HANDLER block which was created when the
   exception was caught and pushes "NULL" to the stack.

All of the following opcodes use their arguments.

STORE_NAME(namei)

   Implements "name = TOS". *namei* is the index of *name* in the
   attribute "co_names" of the code object. The compiler tries to use
   "STORE_FAST" or "STORE_GLOBAL" if possible.

DELETE_NAME(namei)

   Implements "del name", where *namei* is the index into "co_names"
   attribute of the code object.

UNPACK_SEQUENCE(count)

   Unpacks TOS into *count* individual values, which are put onto the
   stack right-to-left.

UNPACK_EX(counts)

   Implements assignment with a starred target: Unpacks an iterable in
   TOS into individual values, where the total number of values can be
   smaller than the number of items in the iterable: one of the new
   values will be a list of all leftover items.

   The low byte of *counts* is the number of values before the list
   value, the high byte of *counts* the number of values after it.
   The resulting values are put onto the stack right-to-left.

STORE_ATTR(namei)

   Implements "TOS.name = TOS1", where *namei* is the index of name in
   "co_names".

DELETE_ATTR(namei)

   Implements "del TOS.name", using *namei* as index into "co_names".

STORE_GLOBAL(namei)

   Works as "STORE_NAME", but stores the name as a global.

DELETE_GLOBAL(namei)

   Works as "DELETE_NAME", but deletes a global name.

LOAD_CONST(consti)

   Pushes "co_consts[consti]" onto the stack.

LOAD_NAME(namei)

   Pushes the value associated with "co_names[namei]" onto the stack.

BUILD_TUPLE(count)

   Creates a tuple consuming *count* items from the stack, and pushes
   the resulting tuple onto the stack.

BUILD_LIST(count)

   Works as "BUILD_TUPLE", but creates a list.

BUILD_SET(count)

   Works as "BUILD_TUPLE", but creates a set.

BUILD_MAP(count)

   Pushes a new dictionary object onto the stack.  Pops "2 * count"
   items so that the dictionary holds *count* entries: "{..., TOS3:
   TOS2, TOS1: TOS}".

   3.5 版更變: The dictionary is created from stack items instead of
   creating an empty dictionary pre-sized to hold *count* items.

BUILD_CONST_KEY_MAP(count)

   The version of "BUILD_MAP" specialized for constant keys.  *count*
   values are consumed from the stack.  The top element on the stack
   contains a tuple of keys.

   3.6 版新加入.

BUILD_STRING(count)

   Concatenates *count* strings from the stack and pushes the
   resulting string onto the stack.

   3.6 版新加入.

BUILD_TUPLE_UNPACK(count)

   Pops *count* iterables from the stack, joins them in a single
   tuple, and pushes the result.  Implements iterable unpacking in
   tuple displays "(*x, *y, *z)".

   3.5 版新加入.

BUILD_TUPLE_UNPACK_WITH_CALL(count)

   This is similar to "BUILD_TUPLE_UNPACK", but is used for "f(*x, *y,
   *z)" call syntax. The stack item at position "count + 1" should be
   the corresponding callable "f".

   3.6 版新加入.

BUILD_LIST_UNPACK(count)

   This is similar to "BUILD_TUPLE_UNPACK", but pushes a list instead
   of tuple.  Implements iterable unpacking in list displays "[*x, *y,
   *z]".

   3.5 版新加入.

BUILD_SET_UNPACK(count)

   This is similar to "BUILD_TUPLE_UNPACK", but pushes a set instead
   of tuple.  Implements iterable unpacking in set displays "{*x, *y,
   *z}".

   3.5 版新加入.

BUILD_MAP_UNPACK(count)

   Pops *count* mappings from the stack, merges them into a single
   dictionary, and pushes the result.  Implements dictionary unpacking
   in dictionary displays "{**x, **y, **z}".

   3.5 版新加入.

BUILD_MAP_UNPACK_WITH_CALL(count)

   This is similar to "BUILD_MAP_UNPACK", but is used for "f(**x, **y,
   **z)" call syntax.  The stack item at position "count + 2" should
   be the corresponding callable "f".

   3.5 版新加入.

   3.6 版更變: The position of the callable is determined by adding 2
   to the opcode argument instead of encoding it in the second byte of
   the argument.

LOAD_ATTR(namei)

   Replaces TOS with "getattr(TOS, co_names[namei])".

COMPARE_OP(opname)

   Performs a Boolean operation.  The operation name can be found in
   "cmp_op[opname]".

IMPORT_NAME(namei)

   Imports the module "co_names[namei]".  TOS and TOS1 are popped and
   provide the *fromlist* and *level* arguments of "__import__()".
   The module object is pushed onto the stack.  The current namespace
   is not affected: for a proper import statement, a subsequent
   "STORE_FAST" instruction modifies the namespace.

IMPORT_FROM(namei)

   Loads the attribute "co_names[namei]" from the module found in TOS.
   The resulting object is pushed onto the stack, to be subsequently
   stored by a "STORE_FAST" instruction.

JUMP_FORWARD(delta)

   Increments bytecode counter by *delta*.

POP_JUMP_IF_TRUE(target)

   If TOS is true, sets the bytecode counter to *target*.  TOS is
   popped.

   3.1 版新加入.

POP_JUMP_IF_FALSE(target)

   If TOS is false, sets the bytecode counter to *target*.  TOS is
   popped.

   3.1 版新加入.

JUMP_IF_TRUE_OR_POP(target)

   If TOS is true, sets the bytecode counter to *target* and leaves
   TOS on the stack.  Otherwise (TOS is false), TOS is popped.

   3.1 版新加入.

JUMP_IF_FALSE_OR_POP(target)

   If TOS is false, sets the bytecode counter to *target* and leaves
   TOS on the stack.  Otherwise (TOS is true), TOS is popped.

   3.1 版新加入.

JUMP_ABSOLUTE(target)

   Set bytecode counter to *target*.

FOR_ITER(delta)

   TOS is an *iterator*.  Call its "__next__()" method.  If this
   yields a new value, push it on the stack (leaving the iterator
   below it).  If the iterator indicates it is exhausted TOS is
   popped, and the byte code counter is incremented by *delta*.

LOAD_GLOBAL(namei)

   Loads the global named "co_names[namei]" onto the stack.

SETUP_FINALLY(delta)

   Pushes a try block from a try-finally or try-except clause onto the
   block stack.  *delta* points to the finally block or the first
   except block.

CALL_FINALLY(delta)

   Pushes the address of the next instruction onto the stack and
   increments bytecode counter by *delta*.  Used for calling the
   finally block as a "subroutine".

   3.8 版新加入.

LOAD_FAST(var_num)

   Pushes a reference to the local "co_varnames[var_num]" onto the
   stack.

STORE_FAST(var_num)

   Stores TOS into the local "co_varnames[var_num]".

DELETE_FAST(var_num)

   Deletes local "co_varnames[var_num]".

LOAD_CLOSURE(i)

   Pushes a reference to the cell contained in slot *i* of the cell
   and free variable storage.  The name of the variable is
   "co_cellvars[i]" if *i* is less than the length of *co_cellvars*.
   Otherwise it is "co_freevars[i - len(co_cellvars)]".

LOAD_DEREF(i)

   Loads the cell contained in slot *i* of the cell and free variable
   storage. Pushes a reference to the object the cell contains on the
   stack.

LOAD_CLASSDEREF(i)

   Much like "LOAD_DEREF" but first checks the locals dictionary
   before consulting the cell.  This is used for loading free
   variables in class bodies.

   3.4 版新加入.

STORE_DEREF(i)

   Stores TOS into the cell contained in slot *i* of the cell and free
   variable storage.

DELETE_DEREF(i)

   Empties the cell contained in slot *i* of the cell and free
   variable storage. Used by the "del" statement.

   3.2 版新加入.

RAISE_VARARGS(argc)

   Raises an exception using one of the 3 forms of the "raise"
   statement, depending on the value of *argc*:

   * 0: "raise" (re-raise previous exception)

   * 1: "raise TOS" (raise exception instance or type at "TOS")

   * 2: "raise TOS1 from TOS" (raise exception instance or type at
     "TOS1" with "__cause__" set to "TOS")

CALL_FUNCTION(argc)

   Calls a callable object with positional arguments. *argc* indicates
   the number of positional arguments. The top of the stack contains
   positional arguments, with the right-most argument on top.  Below
   the arguments is a callable object to call. "CALL_FUNCTION" pops
   all arguments and the callable object off the stack, calls the
   callable object with those arguments, and pushes the return value
   returned by the callable object.

   3.6 版更變: This opcode is used only for calls with positional
   arguments.

CALL_FUNCTION_KW(argc)

   Calls a callable object with positional (if any) and keyword
   arguments. *argc* indicates the total number of positional and
   keyword arguments. The top element on the stack contains a tuple of
   keyword argument names. Below that are keyword arguments in the
   order corresponding to the tuple. Below that are positional
   arguments, with the right-most parameter on top.  Below the
   arguments is a callable object to call. "CALL_FUNCTION_KW" pops all
   arguments and the callable object off the stack, calls the callable
   object with those arguments, and pushes the return value returned
   by the callable object.

   3.6 版更變: Keyword arguments are packed in a tuple instead of a
   dictionary, *argc* indicates the total number of arguments.

CALL_FUNCTION_EX(flags)

   Calls a callable object with variable set of positional and keyword
   arguments.  If the lowest bit of *flags* is set, the top of the
   stack contains a mapping object containing additional keyword
   arguments. Below that is an iterable object containing positional
   arguments and a callable object to call.
   "BUILD_MAP_UNPACK_WITH_CALL" and "BUILD_TUPLE_UNPACK_WITH_CALL" can
   be used for merging multiple mapping objects and iterables
   containing arguments. Before the callable is called, the mapping
   object and iterable object are each "unpacked" and their contents
   passed in as keyword and positional arguments respectively.
   "CALL_FUNCTION_EX" pops all arguments and the callable object off
   the stack, calls the callable object with those arguments, and
   pushes the return value returned by the callable object.

   3.6 版新加入.

LOAD_METHOD(namei)

   Loads a method named "co_names[namei]" from TOS object. TOS is
   popped and method and TOS are pushed when interpreter can call
   unbound method directly. TOS will be used as the first argument
   ("self") by "CALL_METHOD". Otherwise, "NULL" and  method is pushed
   (method is bound method or something else).

   3.7 版新加入.

CALL_METHOD(argc)

   Calls a method.  *argc* is number of positional arguments. Keyword
   arguments are not supported.  This opcode is designed to be used
   with "LOAD_METHOD".  Positional arguments are on top of the stack.
   Below them, two items described in "LOAD_METHOD" on the stack. All
   of them are popped and return value is pushed.

   3.7 版新加入.

MAKE_FUNCTION(argc)

   Pushes a new function object on the stack.  From bottom to top, the
   consumed stack must consist of values if the argument carries a
   specified flag value

   * "0x01" a tuple of default values for positional-only and
     positional-or-keyword parameters in positional order

   * "0x02" a dictionary of keyword-only parameters' default values

   * "0x04" an annotation dictionary

   * "0x08" a tuple containing cells for free variables, making a
     closure

   * the code associated with the function (at TOS1)

   * the *qualified name* of the function (at TOS)

BUILD_SLICE(argc)

   Pushes a slice object on the stack.  *argc* must be 2 or 3.  If it
   is 2, "slice(TOS1, TOS)" is pushed; if it is 3, "slice(TOS2, TOS1,
   TOS)" is pushed. See the "slice()" built-in function for more
   information.

EXTENDED_ARG(ext)

   Prefixes any opcode which has an argument too big to fit into the
   default one byte. *ext* holds an additional byte which act as
   higher bits in the argument. For each opcode, at most three
   prefixal "EXTENDED_ARG" are allowed, forming an argument from two-
   byte to four-byte.

FORMAT_VALUE(flags)

   Used for implementing formatted literal strings (f-strings).  Pops
   an optional *fmt_spec* from the stack, then a required *value*.
   *flags* is interpreted as follows:

   * "(flags & 0x03) == 0x00": *value* is formatted as-is.

   * "(flags & 0x03) == 0x01": call "str()" on *value* before
     formatting it.

   * "(flags & 0x03) == 0x02": call "repr()" on *value* before
     formatting it.

   * "(flags & 0x03) == 0x03": call "ascii()" on *value* before
     formatting it.

   * "(flags & 0x04) == 0x04": pop *fmt_spec* from the stack and use
     it, else use an empty *fmt_spec*.

   Formatting is performed using "PyObject_Format()".  The result is
   pushed on the stack.

   3.6 版新加入.

HAVE_ARGUMENT

   This is not really an opcode.  It identifies the dividing line
   between opcodes which don't use their argument and those that do
   ("< HAVE_ARGUMENT" and ">= HAVE_ARGUMENT", respectively).

   3.6 版更變: Now every instruction has an argument, but opcodes "<
   HAVE_ARGUMENT" ignore it. Before, only opcodes ">= HAVE_ARGUMENT"
   had an argument.


Opcode collections
==================

These collections are provided for automatic introspection of bytecode
instructions:

dis.opname

   Sequence of operation names, indexable using the bytecode.

dis.opmap

   Dictionary mapping operation names to bytecodes.

dis.cmp_op

   Sequence of all compare operation names.

dis.hasconst

   Sequence of bytecodes that access a constant.

dis.hasfree

   Sequence of bytecodes that access a free variable (note that 'free'
   in this context refers to names in the current scope that are
   referenced by inner scopes or names in outer scopes that are
   referenced from this scope.  It does *not* include references to
   global or builtin scopes).

dis.hasname

   Sequence of bytecodes that access an attribute by name.

dis.hasjrel

   Sequence of bytecodes that have a relative jump target.

dis.hasjabs

   Sequence of bytecodes that have an absolute jump target.

dis.haslocal

   Sequence of bytecodes that access a local variable.

dis.hascompare

   Sequence of bytecodes of Boolean operations.
