How to use the pydriller.domain.commit.Method function in PyDriller

def _calculate_metrics(self):
        if self.source_code and self._nloc is None:
            analysis = lizard.analyze_file.analyze_source_code(self.filename,
                                                               self.source_code
                                                               )

            self._nloc = analysis.nloc
            self._complexity = analysis.CCN
            self._token_count = analysis.token_count

            for func in analysis.function_list:
                self._function_list.append(Method(func))