input: Write a function to multiply two input numbers and print the result. The function should take two parameters, both of which are integers, and return None.
  assert multiply(3, 4) == None
  assert multiply(5, 6) == None
  assert multiply(7, 8) == None
  assert multiply(9, 10) == None
  assert multiply(-1, -5) == None
output: def multiply(a, b):
      print(a * b)