input: Write a function to generate a random number between the given input numbers. The function should take two parameters, start and stop, and return a random integer within the range [start, stop].
  assert random_num(0, 10)==5
  assert random_num(10, 20)==15
  assert random_num(-10, 0)==-5
  assert random_num(100, 200)==150
  assert random_num(-50, 50)==0
output: import random
  
  def random_num(start, stop):
      return random.randint(start, stop)