2. Análise Léxica¶
Um programa Python é lido por um analisador. A entrada para o analisador é um fluxo de tokens, gerado pelo analisador lexical. Este capítulo descreve como o analisador lexical divide um arquivo em tokens.
Python lê o texto do programa como pontos de código Unicode; a codificação de um arquivo de origem pode ser fornecida por uma declaração de codificação que por padrão é UTF-8, consulte PEP 3120 para obter detalhes. Se o arquivo de origem não puder ser decodificado, um: exc:SyntaxError será gerado.
2.1. Estrutura da Linha¶
Um programa Python é dividido em uma série de linhas lógicas.
2.1.1. Linhas Lógicas¶
O fim de uma linha lógica é representado pelo token NEWLINE. As declarações não podem cruzar os limites da linha lógica, exceto onde NEWLINE for permitido pela sintaxe (por exemplo, entre as declarações de declarações compostas). Uma linha lógica é construída a partir de uma ou mais linhas físicas seguindo a linha explícita ou implícita que junta as linhas das regras.
2.1.2. Linha Física¶
Uma linha física é uma sequência de caracteres terminados por uma sequência de quebra de linha. Nos arquivos de origem e cadeias de caracteres, qualquer uma das sequências de terminação de linha de plataforma padrão pode ser usada - o formato Unix usando ASCII LF (linefeed), o formato Windows usando a sequência ASCII CR LF (return followed by linefeed) ou o antigo formato Macintosh usando o caractere ASCII CR (return). Todos esses formatos podem ser usados igualmente, independentemente da plataforma. O final da entrada também serve como um finalizador implícito para a linha física final.
Ao incorporar o Python, o código-fonte das Strings devem ser passadas para APIs do Python usando as convenções C padrão para caracteres de nova linha (o caractere \n, representando ASCII LF, será o terminador de linha).
2.1.4. Declarações de codificação¶
If a comment in the first or second line of the Python script matches the
regular expression coding[=:]\s*([-\w.]+), this comment is processed as an
encoding declaration; the first group of this expression names the encoding of
the source code file. The encoding declaration must appear on a line of its
own. If it is the second line, the first line must also be a comment-only line.
The recommended forms of an encoding expression are
# -*- coding: <encoding-name> -*-
que é reconhecido também por GNU Emacs, e:
# vim:fileencoding=<encoding-name>
que é reconhecido pelo VIM de Bram Moolenaar.
If no encoding declaration is found, the default encoding is UTF-8. In
addition, if the first bytes of the file are the UTF-8 byte-order mark
(b'\xef\xbb\xbf'), the declared file encoding is UTF-8 (this is supported,
among others, by Microsoft’s notepad).
If an encoding is declared, the encoding name must be recognized by Python. The encoding is used for all lexical analysis, including string literals, comments and identifiers.
2.1.5. Junção de linha explícita¶
Two or more physical lines may be joined into logical lines using backslash
characters (\), as follows: when a physical line ends in a backslash that is
not part of a string literal or comment, it is joined with the following forming
a single logical line, deleting the backslash and the following end-of-line
character. For example:
if 1900 < year < 2100 and 1 <= month <= 12 \
and 1 <= day <= 31 and 0 <= hour < 24 \
and 0 <= minute < 60 and 0 <= second < 60: # Looks like a valid date
return 1
A line ending in a backslash cannot carry a comment. A backslash does not continue a comment. A backslash does not continue a token except for string literals (i.e., tokens other than string literals cannot be split across physical lines using a backslash). A backslash is illegal elsewhere on a line outside a string literal.
2.1.6. Junção de linha implicita¶
Expressions in parentheses, square brackets or curly braces can be split over more than one physical line without using backslashes. For example:
month_names = ['Januari', 'Februari', 'Maart', # These are the
'April', 'Mei', 'Juni', # Dutch names
'Juli', 'Augustus', 'September', # for the months
'Oktober', 'November', 'December'] # of the year
Implicitly continued lines can carry comments. The indentation of the continuation lines is not important. Blank continuation lines are allowed. There is no NEWLINE token between implicit continuation lines. Implicitly continued lines can also occur within triple-quoted strings (see below); in that case they cannot carry comments.
2.1.7. Linhas em Branco¶
A logical line that contains only spaces, tabs, formfeeds and possibly a comment, is ignored (i.e., no NEWLINE token is generated). During interactive input of statements, handling of a blank line may differ depending on the implementation of the read-eval-print loop. In the standard interactive interpreter, an entirely blank logical line (i.e. one containing not even whitespace or a comment) terminates a multi-line statement.
2.1.8. Indentação¶
Leading whitespace (spaces and tabs) at the beginning of a logical line is used to compute the indentation level of the line, which in turn is used to determine the grouping of statements.
Tabs are replaced (from left to right) by one to eight spaces such that the total number of characters up to and including the replacement is a multiple of eight (this is intended to be the same rule as used by Unix). The total number of spaces preceding the first non-blank character then determines the line’s indentation. Indentation cannot be split over multiple physical lines using backslashes; the whitespace up to the first backslash determines the indentation.
Indentation is rejected as inconsistent if a source file mixes tabs and spaces
in a way that makes the meaning dependent on the worth of a tab in spaces; a
TabError is raised in that case.
Cross-platform compatibility note: because of the nature of text editors on non-UNIX platforms, it is unwise to use a mixture of spaces and tabs for the indentation in a single source file. It should also be noted that different platforms may explicitly limit the maximum indentation level.
A formfeed character may be present at the start of the line; it will be ignored for the indentation calculations above. Formfeed characters occurring elsewhere in the leading whitespace have an undefined effect (for instance, they may reset the space count to zero).
The indentation levels of consecutive lines are used to generate INDENT and DEDENT tokens, using a stack, as follows.
Before the first line of the file is read, a single zero is pushed on the stack; this will never be popped off again. The numbers pushed on the stack will always be strictly increasing from bottom to top. At the beginning of each logical line, the line’s indentation level is compared to the top of the stack. If it is equal, nothing happens. If it is larger, it is pushed on the stack, and one INDENT token is generated. If it is smaller, it must be one of the numbers occurring on the stack; all numbers on the stack that are larger are popped off, and for each number popped off a DEDENT token is generated. At the end of the file, a DEDENT token is generated for each number remaining on the stack that is larger than zero.
Here is an example of a correctly (though confusingly) indented piece of Python code:
def perm(l):
# Compute the list of all permutations of l
if len(l) <= 1:
return [l]
r = []
for i in range(len(l)):
s = l[:i] + l[i+1:]
p = perm(s)
for x in p:
r.append(l[i:i+1] + x)
return r
The following example shows various indentation errors:
def perm(l): # error: first line indented
for i in range(len(l)): # error: not indented
s = l[:i] + l[i+1:]
p = perm(l[:i] + l[i+1:]) # error: unexpected indent
for x in p:
r.append(l[i:i+1] + x)
return r # error: inconsistent dedent
(Actually, the first three errors are detected by the parser; only the last
error is found by the lexical analyzer — the indentation of return r does
not match a level popped off the stack.)
2.1.9. Espaços em branco entre tokens¶
Except at the beginning of a logical line or in string literals, the whitespace characters space, tab and formfeed can be used interchangeably to separate tokens. Whitespace is needed between two tokens only if their concatenation could otherwise be interpreted as a different token (e.g., ab is one token, but a b is two tokens).
2.2. Outros Tokens¶
Besides NEWLINE, INDENT and DEDENT, the following categories of tokens exist: identifiers, keywords, literals, operators, and delimiters. Whitespace characters (other than line terminators, discussed earlier) are not tokens, but serve to delimit tokens. Where ambiguity exists, a token comprises the longest possible string that forms a legal token, when read from left to right.
2.3. Identificadores e Keywords¶
Identifiers (also referred to as names) are described by the following lexical definitions.
The syntax of identifiers in Python is based on the Unicode standard annex UAX-31, with elaboration and changes as defined below; see also PEP 3131 for further details.
Within the ASCII range (U+0001..U+007F), the valid characters for identifiers
are the same as in Python 2.x: the uppercase and lowercase letters A through
Z, the underscore _ and, except for the first character, the digits
0 through 9.
Python 3.0 introduces additional characters from outside the ASCII range (see
PEP 3131). For these characters, the classification uses the version of the
Unicode Character Database as included in the unicodedata module.
Identifiers are unlimited in length. Case is significant.
identifier ::=xid_startxid_continue* id_start ::= <all characters in general categories Lu, Ll, Lt, Lm, Lo, Nl, the underscore, and characters with the Other_ID_Start property> id_continue ::= <all characters inid_start, plus characters in the categories Mn, Mc, Nd, Pc and others with the Other_ID_Continue property> xid_start ::= <all characters inid_startwhose NFKC normalization is in "id_start xid_continue*"> xid_continue ::= <all characters inid_continuewhose NFKC normalization is in "id_continue*">
The Unicode category codes mentioned above stand for:
Lu - letras maiúsculas
Ll - letras minúsculas
Lt - letras de titlecase
Lm - letras modificadoras
Lo - outras letras
Nl - letras numéricas
Mn - marcas sem espaçamentos
Mc - marcas de combinação de espaçamento
Nd - números decimais
Pc - pontuações de conectores
Other_ID_Start - explicit list of characters in PropList.txt to support backwards compatibility
Other_ID_Continue - likewise
All identifiers are converted into the normal form NFKC while parsing; comparison of identifiers is based on NFKC.
A non-normative HTML file listing all valid identifier characters for Unicode 4.1 can be found at https://www.unicode.org/Public/13.0.0/ucd/DerivedCoreProperties.txt
2.3.1. Keywords¶
The following identifiers are used as reserved words, or keywords of the language, and cannot be used as ordinary identifiers. They must be spelled exactly as written here:
False await else import pass
None break except in raise
True class finally is return
and continue for lambda try
as def from nonlocal while
assert del global not with
async elif if or yield
2.3.2. Classes reservadas de identificadores¶
Certas classes de identificadores (além de keywords) possuem significados especiais. Essas classes são identificadas pelos padrões de caracteres de sublinhado principais e à direita:
_*Not imported by
from module import *. The special identifier_is used in the interactive interpreter to store the result of the last evaluation; it is stored in thebuiltinsmodule. When not in interactive mode,_has no special meaning and is not defined. See section A instrução import.Nota
The name
_is often used in conjunction with internationalization; refer to the documentation for thegettextmodule for more information on this convention.__*__System-defined names, informally known as “dunder” names. These names are defined by the interpreter and its implementation (including the standard library). Current system names are discussed in the Nomes de métodos especiais section and elsewhere. More will likely be defined in future versions of Python. Any use of
__*__names, in any context, that does not follow explicitly documented use, is subject to breakage without warning.__*Class-private names. Names in this category, when used within the context of a class definition, are re-written to use a mangled form to help avoid name clashes between “private” attributes of base and derived classes. See section Identificadores (Nomes).
2.4. Literais¶
Os literais são notações para valores constantes de alguns tipos incorporados.
2.4.1. String e Bytes literais¶
String literals are described by the following lexical definitions:
stringliteral ::= [stringprefix](shortstring|longstring) stringprefix ::= "r" | "u" | "R" | "U" | "f" | "F" | "fr" | "Fr" | "fR" | "FR" | "rf" | "rF" | "Rf" | "RF" shortstring ::= "'"shortstringitem* "'" | '"'shortstringitem* '"' longstring ::= "'''"longstringitem* "'''" | '"""'longstringitem* '"""' shortstringitem ::=shortstringchar|stringescapeseqlongstringitem ::=longstringchar|stringescapeseqshortstringchar ::= <any source character except "\" or newline or the quote> longstringchar ::= <any source character except "\"> stringescapeseq ::= "\" <any source character>
bytesliteral ::=bytesprefix(shortbytes|longbytes) bytesprefix ::= "b" | "B" | "br" | "Br" | "bR" | "BR" | "rb" | "rB" | "Rb" | "RB" shortbytes ::= "'"shortbytesitem* "'" | '"'shortbytesitem* '"' longbytes ::= "'''"longbytesitem* "'''" | '"""'longbytesitem* '"""' shortbytesitem ::=shortbyteschar|bytesescapeseqlongbytesitem ::=longbyteschar|bytesescapeseqshortbyteschar ::= <any ASCII character except "\" or newline or the quote> longbyteschar ::= <any ASCII character except "\"> bytesescapeseq ::= "\" <any ASCII character>
One syntactic restriction not indicated by these productions is that whitespace
is not allowed between the stringprefix or bytesprefix and the
rest of the literal. The source character set is defined by the encoding
declaration; it is UTF-8 if no encoding declaration is given in the source file;
see section Declarações de codificação.
In plain English: Both types of literals can be enclosed in matching single quotes
(') or double quotes ("). They can also be enclosed in matching groups
of three single or double quotes (these are generally referred to as
triple-quoted strings). The backslash (\) character is used to escape
characters that otherwise have a special meaning, such as newline, backslash
itself, or the quote character.
Bytes literals are always prefixed with 'b' or 'B'; they produce an
instance of the bytes type instead of the str type. They
may only contain ASCII characters; bytes with a numeric value of 128 or greater
must be expressed with escapes.
Both string and bytes literals may optionally be prefixed with a letter 'r'
or 'R'; such strings are called raw strings and treat backslashes as
literal characters. As a result, in string literals, '\U' and '\u'
escapes in raw strings are not treated specially. Given that Python 2.x’s raw
unicode literals behave differently than Python 3.x’s the 'ur' syntax
is not supported.
Novo na versão 3.3: The 'rb' prefix of raw bytes literals has been added as a synonym
of 'br'.
Novo na versão 3.3: Support for the unicode legacy literal (u'value') was reintroduced
to simplify the maintenance of dual Python 2.x and 3.x codebases.
See PEP 414 for more information.
A string literal with 'f' or 'F' in its prefix is a
formatted string literal; see Literais de string formatados. The 'f' may be
combined with 'r', but not with 'b' or 'u', therefore raw
formatted strings are possible, but formatted bytes literals are not.
In triple-quoted literals, unescaped newlines and quotes are allowed (and are
retained), except that three unescaped quotes in a row terminate the literal. (A
“quote” is the character used to open the literal, i.e. either ' or ".)
Unless an 'r' or 'R' prefix is present, escape sequences in string and
bytes literals are interpreted according to rules similar to those used by
Standard C. The recognized escape sequences are:
Caracteres de Escapes (Escapes Sequence) |
Significado |
Notas |
|---|---|---|
|
A barra invertida e a nova linha foram ignoradas |
|
|
Backslash ( |
|
|
Aspas Simples ( |
|
|
Aspas Dupla ( |
|
|
ASCII Bell (BEL) |
|
|
ASCII Backspace (BS) |
|
|
ASCII Formfeed (FF) |
|
|
ASCII Linefeed (LF) |
|
|
ASCII Carriage Return (CR) |
|
|
ASCII Horizontal Tab (TAB) |
|
|
ASCII Vertical Tab (VT) |
|
|
Caráter com valor octal ooo |
(1,3) |
|
Caráter com valor hexadecimal hh |
(2,3) |
As sequências de escape apenas reconhecidas em literais de Strings são:
Caracteres de Escapes (Escapes Sequence) |
Significado |
Notas |
|---|---|---|
|
Caractere chamado name no banco de dados Unicode |
(4) |
|
Caractere com valor hexadecimal de 16 bits xxxx |
(5) |
|
Caractere com valor hexadecimal de 32 bits xxxxxxxx |
(6) |
Notas:
Como no padrão C, são aceitos até três dígitos octal.
Ao contrário do padrão C, são necessários exatamente dois dígitos hexadecimais.
In a bytes literal, hexadecimal and octal escapes denote the byte with the given value. In a string literal, these escapes denote a Unicode character with the given value.
Alterado na versão 3.3: O suporte para apelidos de nome 1 foram adicionado.
São necessários quatro dígitos hexadecimais.
Any Unicode character can be encoded this way. Exactly eight hex digits are required.
Unlike Standard C, all unrecognized escape sequences are left in the string unchanged, i.e., the backslash is left in the result. (This behavior is useful when debugging: if an escape sequence is mistyped, the resulting output is more easily recognized as broken.) It is also important to note that the escape sequences only recognized in string literals fall into the category of unrecognized escapes for bytes literals.
Alterado na versão 3.6: Unrecognized escape sequences produce a DeprecationWarning. In some future version of Python they will be a SyntaxError.
Even in a raw literal, quotes can be escaped with a backslash, but the
backslash remains in the result; for example, r"\"" is a valid string
literal consisting of two characters: a backslash and a double quote; r"\"
is not a valid string literal (even a raw string cannot end in an odd number of
backslashes). Specifically, a raw literal cannot end in a single backslash
(since the backslash would escape the following quote character). Note also
that a single backslash followed by a newline is interpreted as those two
characters as part of the literal, not as a line continuation.
2.4.2. String literal concatenation¶
Multiple adjacent string or bytes literals (delimited by whitespace), possibly
using different quoting conventions, are allowed, and their meaning is the same
as their concatenation. Thus, "hello" 'world' is equivalent to
"helloworld". This feature can be used to reduce the number of backslashes
needed, to split long strings conveniently across long lines, or even to add
comments to parts of strings, for example:
re.compile("[A-Za-z_]" # letter or underscore
"[A-Za-z0-9_]*" # letter, digit or underscore
)
Note that this feature is defined at the syntactical level, but implemented at compile time. The ‘+’ operator must be used to concatenate string expressions at run time. Also note that literal concatenation can use different quoting styles for each component (even mixing raw strings and triple quoted strings), and formatted string literals may be concatenated with plain string literals.
2.4.3. Literais de string formatados¶
Novo na versão 3.6.
A formatted string literal or f-string is a string literal
that is prefixed with 'f' or 'F'. These strings may contain
replacement fields, which are expressions delimited by curly braces {}.
While other string literals always have a constant value, formatted strings
are really expressions evaluated at run time.
Escape sequences are decoded like in ordinary string literals (except when a literal is also marked as a raw string). After decoding, the grammar for the contents of the string is:
f_string ::= (literal_char| "{{" | "}}" |replacement_field)* replacement_field ::= "{"f_expression["!"conversion] [":"format_spec] "}" f_expression ::= (conditional_expression| "*"or_expr) (","conditional_expression| "," "*"or_expr)* [","] |yield_expressionconversion ::= "s" | "r" | "a" format_spec ::= (literal_char| NULL |replacement_field)* literal_char ::= <any code point except "{", "}" or NULL>
The parts of the string outside curly braces are treated literally,
except that any doubled curly braces '{{' or '}}' are replaced
with the corresponding single curly brace. A single opening curly
bracket '{' marks a replacement field, which starts with a
Python expression. After the expression, there may be a conversion field,
introduced by an exclamation point '!'. A format specifier may also
be appended, introduced by a colon ':'. A replacement field ends
with a closing curly bracket '}'.
Expressions in formatted string literals are treated like regular
Python expressions surrounded by parentheses, with a few exceptions.
An empty expression is not allowed, and a lambda expression
must be surrounded by explicit parentheses. Replacement expressions
can contain line breaks (e.g. in triple-quoted strings), but they
cannot contain comments. Each expression is evaluated in the context
where the formatted string literal appears, in order from left to right.
Alterado na versão 3.7: Prior to Python 3.7, an await expression and comprehensions
containing an async for clause were illegal in the expressions
in formatted string literals due to a problem with the implementation.
If a conversion is specified, the result of evaluating the expression
is converted before formatting. Conversion '!s' calls str() on
the result, '!r' calls repr(), and '!a' calls ascii().
The result is then formatted using the format() protocol. The
format specifier is passed to the __format__() method of the
expression or conversion result. An empty string is passed when the
format specifier is omitted. The formatted result is then included in
the final value of the whole string.
Top-level format specifiers may include nested replacement fields. These nested fields may include their own conversion fields and format specifiers, but may not include more deeply-nested replacement fields. The format specifier mini-language is the same as that used by the string .format() method.
Formatted string literals may be concatenated, but replacement fields cannot be split across literals.
Alguns exemplos de literais formatados:
>>> name = "Fred"
>>> f"He said his name is {name!r}."
"He said his name is 'Fred'."
>>> f"He said his name is {repr(name)}." # repr() is equivalent to !r
"He said his name is 'Fred'."
>>> width = 10
>>> precision = 4
>>> value = decimal.Decimal("12.34567")
>>> f"result: {value:{width}.{precision}}" # nested fields
'result: 12.35'
>>> today = datetime(year=2017, month=1, day=27)
>>> f"{today:%B %d, %Y}" # using date format specifier
'January 27, 2017'
>>> number = 1024
>>> f"{number:#0x}" # using integer format specifier
'0x400'
A consequence of sharing the same syntax as regular string literals is that characters in the replacement fields must not conflict with the quoting used in the outer formatted string literal:
f"abc {a["x"]} def" # error: outer string literal ended prematurely
f"abc {a['x']} def" # workaround: use different quoting
As barras invertidas não são permitidas nas expressões de formatação e levantarão uma exceção:
f"newline: {ord('\n')}" # raises SyntaxError
To include a value in which a backslash escape is required, create a temporary variable.
>>> newline = ord('\n')
>>> f"newline: {newline}"
'newline: 10'
Formatted string literals cannot be used as docstrings, even if they do not include expressions.
>>> def foo():
... f"Not a docstring"
...
>>> foo.__doc__ is None
True
See also PEP 498 for the proposal that added formatted string literals,
and str.format(), which uses a related format string mechanism.
2.4.4. Literais Numéricos¶
There are three types of numeric literals: integers, floating point numbers, and imaginary numbers. There are no complex literals (complex numbers can be formed by adding a real number and an imaginary number).
Note that numeric literals do not include a sign; a phrase like -1 is
actually an expression composed of the unary operator ‘-’ and the literal
1.
2.4.5. Inteiros Literais¶
Integer literals are described by the following lexical definitions:
integer ::=decinteger|bininteger|octinteger|hexintegerdecinteger ::=nonzerodigit(["_"]digit)* | "0"+ (["_"] "0")* bininteger ::= "0" ("b" | "B") (["_"]bindigit)+ octinteger ::= "0" ("o" | "O") (["_"]octdigit)+ hexinteger ::= "0" ("x" | "X") (["_"]hexdigit)+ nonzerodigit ::= "1"..."9" digit ::= "0"..."9" bindigit ::= "0" | "1" octdigit ::= "0"..."7" hexdigit ::=digit| "a"..."f" | "A"..."F"
There is no limit for the length of integer literals apart from what can be stored in available memory.
Underscores are ignored for determining the numeric value of the literal. They
can be used to group digits for enhanced readability. One underscore can occur
between digits, and after base specifiers like 0x.
Note that leading zeros in a non-zero decimal number are not allowed. This is for disambiguation with C-style octal literals, which Python used before version 3.0.
Alguns exemplos de inteiros literais:
7 2147483647 0o177 0b100110111
3 79228162514264337593543950336 0o377 0xdeadbeef
100_000_000_000 0b_1110_0101
Alterado na versão 3.6: Os underscores agora são permitidos para fins de agrupamento de literais.
2.4.6. Literais de Ponto Flutuante¶
Floating point literals are described by the following lexical definitions:
floatnumber ::=pointfloat|exponentfloatpointfloat ::= [digitpart]fraction|digitpart"." exponentfloat ::= (digitpart|pointfloat)exponentdigitpart ::=digit(["_"]digit)* fraction ::= "."digitpartexponent ::= ("e" | "E") ["+" | "-"]digitpart
Note that the integer and exponent parts are always interpreted using radix 10.
For example, 077e010 is legal, and denotes the same number as 77e10. The
allowed range of floating point literals is implementation-dependent. As in
integer literals, underscores are supported for digit grouping.
Alguns exemplos de literais de ponto flutuante:
3.14 10. .001 1e100 3.14e-10 0e0 3.14_15_93
Alterado na versão 3.6: Os underscores agora são permitidos para fins de agrupamento de literais.
2.4.7. Literais Imaginários¶
Os literais imaginários são descritos pelas seguintes definições léxicas:
imagnumber ::= (floatnumber|digitpart) ("j" | "J")
Um literal imaginário produz um número complexo com uma parte real de 0.0. Os números complexos são representados como um par de números de ponto flutuante e têm as mesmas restrições em seu alcance. Para criar um número complexo com uma parte real diferente de zero, adicione um número de ponto flutuante a ele, por exemplo, (3 + 4j). Alguns exemplos de literais imaginários
3.14j 10.j 10j .001j 1e100j 3.14e-10j 3.14_15_93j
2.5. Operadores¶
Os seguintes tokens são operadores:
+ - * ** / // % @
<< >> & | ^ ~
< > <= >= == !=
2.6. Delimitadores¶
Os seguintes tokens servem como delimitadores na gramática:
( ) [ ] { }
, : . ; @ = ->
+= -= *= /= //= %= @=
&= |= ^= >>= <<= **=
O período também pode ocorrer em literais de ponto flutuante e imaginário. Uma sequência de três períodos tem um significado especial como um literal de elipsis. A segunda metade da lista, os operadores de atribuição aumentada, servem lexicamente como delimitadores, mas também realizam uma operação.
The following printing ASCII characters have special meaning as part of other tokens or are otherwise significant to the lexical analyzer:
' " # \
The following printing ASCII characters are not used in Python. Their occurrence outside string literals and comments is an unconditional error:
$ ? `
Notas de rodapé
2.1.3. Comentários¶
A comment starts with a hash character (
#) that is not part of a string literal, and ends at the end of the physical line. A comment signifies the end of the logical line unless the implicit line joining rules are invoked. Comments are ignored by the syntax.