input: Write a function to compute the sum of two variables and store the result in a third variable, then print the result.
  assert sum_and_store(5, 8)==13
  assert sum_and_store(10, 20)==30
  assert sum_and_store(-5, 5)==0
  assert sum_and_store(0, 0)==0
  assert sum_and_store(7, -3)==4
output: def sum_and_store(a, b):
      result = a + b
      return result