Calculate the number of items in a vector that appear at the same index in each vector, with the same value.
([1 2 3 4 5], [1 2 2 4 3]) => 0.6
([1 2 3], [1 2 3]) => 1.0
Affinity value should be realized on a scale of 0.0 to 1.0, with 1.0 being absolutely identical. Two identical sets should always be evaluated as having an affinity of 1.0.
Hint: The last example test case holds a significant clue to calculating the affinity correctly.