input: Write a function to create a Python generator that returns numbers from a given list. The function should take a list as input and yield each item from the list. If the input list is empty, the generator should not yield any items.
  assert list_generator([1, 3, 5, 7, 9]) is not None
  assert list_generator([]) is not None
output: def list_generator(lst):
      for item in lst:
          yield item