input: Write a python function to generate a random number between two given numbers.
  assert 30 <= random_number(30, 100) < 100
  assert 0 <= random_number(0, 50) < 50
  assert 100 <= random_number(100, 200) < 200
output: import random
  
  def random_number(start, end):
      return random.randint(start, end - 1)