Calculate the Hamming distance between two DNA strands.
We read DNA using the letters C, A, G and T. Two strands might look like this:
GAGCCTACTAACGGGAT
CATCGTAATGACGGCCT
^ ^ ^ ^ ^ ^^
They have 7 differences, and therefore the Hamming distance is 7.
The Hamming distance is only defined for sequences of equal length, so an attempt to calculate it between sequences of different lengths should not work.