Please upload your patch from a Mercurial clone:

* https://docs.python.org/devguide/setup.html#checkout
* https://docs.python.org/devguide/patch.html

Currently, if you pass a string as a second argument, you get:

>>> complex(1, "1")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: complex() second arg can't be a string

So the exception message should probably be changed to include "second arg" or "second argument":

>>> complex(1j, {1: 2})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: complex() second arg must be a number, not 'dict'

Also, there is already a check for second argument in line 952 so the "must be a string" part is probably not needed. We probably need to check whether these two cases can be combined.

You also need to add some tests to Lib/test/test_complex.py.