@staticmethod<EOL><INDENT>def create_not_able_to_convert(source: S, converter: Converter, desired_type: Type[T]):<DEDENT>
base_msg = '<STR_LIT>' + str(converter) + '<STR_LIT>' + str(source) + '<STR_LIT>''<STR_LIT>' + get_pretty_type_str(type(source)) + '<STR_LIT>'+ get_pretty_type_str(desired_type) + '<STR_LIT>'<EOL>base_msg += '<STR_LIT>''<STR_LIT>'<EOL>return ConversionException(base_msg)<EOL>
Helper method provided because we actually can't put that in the constructor, it creates a bug in Nose tests
https://github.com/nose-devs/nose/issues/725

:param source:
:param converter:
:param desired_type:
:return: