Given positive Int n implement a function which returns a list of containing pairs with all combinations of numbers
from 0 to n.
Example 1
getAllPairs(0) [Pair(0, 0)]Example 2
getAllPairs(1) [Pair(0, 0), Pair(0, 1), Pair(1, 0), Pair(1, 1)]Example 3
getAllPairs(2) [Pair(0, 0), Pair(0, 1), Pair(0, 2), Pair(1, 0), Pair(1, 1), Pair(1, 2), Pair(2, 0), Pair(2, 1), Pair(2, 2)]