If there are no numbers in the set then there is no highest
number.
2.Assume the first number in the set is the largest number in
the set.
3.For each remaining number in the set: if this number is larger
than the current largest number, consider this number to be
the largest number in the set.
4.When there are no numbers left in the set to iterate over,
consider the current largest number to be the largest
number of the set.