def print_frames(self):
        for f in self.frames:
            filename = f.f_code.co_filename
            lineno = f.line_number()
            print('  File "%s", line %d, in %s' % (
                filename, lineno, f.f_code.co_name
            ))
            linecache.checkcache(filename)
            line = linecache.getline(filename, lineno, f.f_globals)
            if line:
                print('    ' + line.strip())
Test the factory's deferred on connection faulure.
dataset/ETHPy150Open nedbat/byterun/byterun/pyvm2.py/VirtualMachine.print_frames--crossover with--dataset/ETHPy150Open ralphm/wokkel/wokkel/test/test_client.py/DeferredClientFactoryTest.test_deferredOnConnectionFailure