Python

<code>def add_lists(a, b):
    """
      >>> add_lists([1, 1], [1, 1])
      [2, 2]
      >>> add_lists([1, 2], [1, 4])
      [2, 6]
      >>> add_lists([1, 2, 1], [1, 4, 3])
      [2, 6, 4]
    """
    new_list = []
    i = 0
    while i < len(a):
        new_list += a(i) + b(i)
        i += 1
    return new_list

if __name__ == '__main__':
    import doctest
    doctest.testmod()</code>

TypeError: 'list' object is not callable

How can I fix this?

OP is a huge idiot who deserves to fail every programming exam on his whole life.

That, or one of the best trolls we have had recently. Which means our trolls are quite poor quality indeed.