input: Write a function to create a Python generator that returns numbers from a given list.
  def list_generator(input_list):
      for item in input_list:
          yield item
  
  assert next(list_generator([1,3,5,7,9]))==1
  assert next(list_generator([2,4,6,8]))==2
  assert next(list_generator([10,20,30]))==10
  assert next(list_generator([100,200,300]))==100
  assert next(list_generator([]))==None
output: def list_generator(input_list):
      for item in input_list:
          yield item