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)=='12'
  assert multiply(5, 5)=='25'
  assert multiply(7, -2)=='-14'
  assert multiply(0, 9)=='0'
  assert multiply(-3, -3)=='9'
output: def multiply(a, b):
      result = a * b
      print(result)