<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _GetFormatter(self, format_str):
 """ The user's formatters are consulted first, then the default formatters. """

        formatter, args, func_type = self.formatters.LookupWithType(format_str)
        if formatter:
            return formatter, args, func_type
        else:
            raise BadFormatter('%r is not a valid formatter' % format_str)