Update documentation to mention bytes instead byte string and correct one
mentioned string to the accurate description of what type is required.
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index ad5a535..a0d8471 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -311,7 +311,7 @@
.. function:: check_output(*popenargs, timeout=None, **kwargs)
- Run command with arguments and return its output as a byte string.
+ Run command with arguments and return its output as a bytes object.
If the exit code was non-zero it raises a :exc:`CalledProcessError`. The
:exc:`CalledProcessError` object will have the return code in the
@@ -447,8 +447,9 @@
Interact with process: Send data to stdin. Read data from stdout and stderr,
until end-of-file is reached. Wait for process to terminate. The optional
- *input* argument should be a byte string to be sent to the child process, or
- ``None``, if no data should be sent to the child.
+ *input* argument should be data to be sent to the child process, or
+ ``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)``.