input: Write a function that takes two numbers as input, and generates a random number between them. The function should return the generated random number.
  
  assert random_number_generator(2, 5)>=2 and random_number_generator(2, 5)<=5
  assert random_number_generator(-10, 10)>=-10 and random_number_generator(-10, 10)<=10
output: import random
  
  def random_number_generator(a, b):
      return random.randint(a, b)