Write a function named switchPairs that switches the order of values in a vector of integers in a pairwise fashion.
Your function should accept as a parameter a reference to a vector of integers and should switch the order of the first two values, then switch the order of the next two, switch the order of the next two, and so on.
For example, if the vector initially stores {1, 4, 8, -3, 2, 7},
then your function should switch the first pair, (1 and 4), the second pair (8 and -3) and the third pair (2 and 7) to yield {4, 1, -3, 8, 7, 2}.
If there are an odd number of values in the list, the final element is not moved.
For example, if the original list had been {1, 2, 3, 4, 5},
then the result would be {2, 1, 4, 3, 5}.
