Summary: Constrain format of classname and document Define the format of a valid classname. Updated design doc, function doc and glossary to document format. Error message for case where we have a redefinition of a classname now says why ValueError is raised since we are raising ValueError for incorrect classname format as well. Tests for all cases including verification of cause for ValueError exceptions.

try:
    # Python 2.
    my_input = raw_input
except NameError:
    # Python 3+.
    my_input = input