http://bugs.python.org/review/24420/diff/15059/Doc/library/subprocess.rst File Doc/library/subprocess.rst (right): http://bugs.python.org/review/24420/diff/15059/Doc/library/subprocess.rst#ne... Doc/library/subprocess.rst:880: .. function:: check_output(args, *[, input], stdin=None, stderr=None, shell=False, universal_newlines=False, timeout=None) I think we can now remove *input* from the signature. The following paragraph makes the *input* parameter's presence redundant: + The arguments shown above are merely the most common ones. + The full function signature is largely the same as that of :func:`run` - + most arguments are passed directly through to that interface. + The differences are that explicitly passing ``input=None`` is not + supported, and that *stdout* is not permitted as an argument, as + it is used internally to collect the output from the subprocess. Also, without ``[, input],``, the signature looks more readable to me. http://bugs.python.org/review/24420/