UsersLookup Splits screen_name by Characters When Passed a str #535

When passing UsersLookup screen_name='foouser', screen_name will get turned into 'f,o,o,u,s,e,r'.
It looks like screen_name can be a string by looking at the first part of the following:
screen_name (str, optional): A list of screen_names to retrieve extended information.

LookupFriendship does type checking on screen_name to determine if its a tuple, list, User, or str.