input: Write a python function to check if one list is a permutation of another.
  assert isPermutation([1, 2, 3], [3, 2, 1]) == True
  assert isPermutation([1, 2, 3], [4, 5, 6]) == False
  assert isPermutation([1, 2, 3], [1, 2, 3, 4]) == False
  assert isPermutation([], []) == True
output: def isPermutation(list1, list2):
      return sorted(list1) == sorted(list2)