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, 2)==10
  assert multiply(-1, 6)==-6
  assert multiply(0, 7)==0
output: def multiply(a, b):
      result = a * b
      print(result)