quopri.py's functions encodestring and decodestring are documented to handle strings; and this is clearly suggested by their name. However, these functions accept and return bytes, not strings. This should be reflected in the documentation. 

Even better: deprecate these functions and introduce new ones with behaviour as suggested by their names: encode_string, encode_bytes etc.

The encode() and decode() functions also expect binary file objects.

Attached a patch that changes documentation and docstrings. Removed the mentions of readline(), because read() is called on input instead, if the binascii module is available. Also removed the repeated descriptions of quotetabs and header in encodestring()'s docs.