input: Write a function to compute the sum of two variables and store the result in a third variable. Print the result.
  assert sum_and_store(5, 8)==13
  assert sum_and_store(10, 20)==30
  assert sum_and_store(0, 0)==0
  assert sum_and_store(-1, 1)==0
  assert sum_and_store(-5, -3)==-8
output: def sum_and_store(a, b):
      result = a + b
      return result