input: Write a function to create a Python program that multiplies two input numbers and prints the result. Define the function `multiply` which takes two parameters `a` and `b`, multiplies them, and prints the product. If the given numbers are empty then print "Input is empty".
  assert multiply(3, 4)=="12"
  assert multiply(0, 0)=="0"
  assert multiply(-1, 5)=="-5"
  assert multiply(2.5, 4)=="10.0"
  assert multiply(None, None)=="Input is empty"
output: def multiply(a, b):
      if a is None or b is None:
          print("Input is empty")
      else:
          print(str(a * b))