input: Write a function to multiply two input numbers and print the result.
  def multiply(a, b):
      result = a * b
      print(result)
  
  assert multiply(3, 4)==None
  assert multiply(5, -2)==None
  assert multiply(0, 10)==None
  assert multiply(-3, -3)==None
  assert multiply(7, 0)==None
output: def multiply(a, b):
      result = a * b
      print(result)