# Fixed XOR

Write a function that takes two equal-length buffers and produces
their XOR combination.

If your function works properly, then when you feed it the string:

    1c0111001f010100061a024b53535009181c

... after hex decoding, and when XOR'd against:

    686974207468652062756c6c277320657965

... should produce:

    746865206b696420646f6e277420706c6179