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/Lib/subprocess.py b/Lib/subprocess.py
index cd8aa6b..c5128d8 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -817,8 +817,8 @@
def communicate(self, input=None, timeout=None):
"""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
- string to be sent to the child process, or None, if no data
+ process to terminate. The optional input argument should be
+ bytes to be sent to the child process, or None, if no data
should be sent to the child.
communicate() returns a tuple (stdout, stderr)."""