def diff(self, other, filename_1, filename_2):
        text_1, text_2 = str(self), str(other)
        lines_1 = text_1.split('\n')
        lines_2 = text_2.split('\n')
        diff = unified_diff(lines_1, lines_2, filename_1, filename_2)
        return '\n'.join([line for line in diff])
Return a ``diff`` style unified diff listing between the sha_names of
dataset/ETHPy150Open python-openxml/opc-diag/features/steps/step_data.py/_Manifest.diff