These functions create new file objects.
'w'. The bufsize argument has the same meaning as the corresponding argument to the built-in open() function. The exit status of the command (encoded in the format specified for wait()) is available as the return value of the close() method of the file object, except that when the exit status is zero (termination without errors),
Noneis returned. Note: This function behaves unreliably under Windows due to the native implementation of popen(). Availability: Unix, Windows.