Right function "enum_types" in "mimetypes.py"

def enum_types(mimedb):
    i = 0
    while True:
        try:
            ctype = _winreg.EnumKey(mimedb, i)
        except EnvironmentError:
            break
        try:
            ctype = ctype.encode(default_encoding) # omit in 3.x!
        except UnicodeError:
            pass
        else:
            yield ctype
        i += 1