input: Write a function to multiply two input numbers and print the result. Given two numbers, the function should return the product of these two numbers.
  assert multiply(3, 4)==12
  assert multiply(5, 2)==10
  assert multiply(7, 8)==56
  assert multiply(1, 1)==1
  assert multiply(0, 9)==0
output: def multiply(a, b):
      return a * b