input: Write a function that takes two numbers as input and prints the sum of these two numbers.
  
  assert add(5, 7) == 12
  assert add(3, -1) == 2
  assert add(0, 0) == 0
  assert add(-3, -2) == -5
  assert add(10, -5) == 5
output: def add(a, b):
      return a + b