'The entry method for doctest output checking. Defers to a sequence of
child checkers'

def check_output(self, want, got, optionflags):

    checks = (self.check_output_default, self.check_output_numeric, self.check_output_xml, self.check_output_json)
    for check in checks:
        if check(want, got, optionflags):
            return True
    return False
