input: Write a python function to compare two numbers and return which one is greater.
  assert compare_numbers(5, 3) == "A is greater than B"
  assert compare_numbers(2, 4) == "B is greater than A"
  assert compare_numbers(7, 7) == "A is equal to B"
output: def compare_numbers(A, B):
      if A > B:
          return "A is greater than B"
      elif A < B:
          return "B is greater than A"
      else:
          return "A is equal to B"