``None``, if no data should be sent to the child. The type of *input*
must be bytes or, if *universal_newlines* was ``True``, a string.
- :meth:`communicate` returns a tuple ``(stdoutdata, stderrdata)``.
+ :meth:`communicate` returns a tuple ``(stdout_data, stderr_data)``.
+ The data will be bytes or, if *universal_newlines* was ``True``, strings.
Note that if you want to send data to the process's stdin, you need to create
the Popen object with ``stdin=PIPE``. Similarly, to get anything other than