from dis import dis, _s def f(a): for i in range(100000): a.append(i) a = 0.5 a = True a = '123' a = 123, 456 a = [1, 2, 3] return a, a, a def g(a): return f([1,2,3] + a) # x = _s(g) # assert type(x) is str