input: Write a python function to remove all instances of a given item from a list.
  assert remove_item([1, 2, 3, 4], 2) == [1, 3, 4]
  assert remove_item([1, 2, 2, 2, 3, 4], 2) == [1, 3, 4]
  assert remove_item([1, 2, 3, 4, 5], 5) == [1, 2, 3, 4]
output: def remove_item(lst, item):
      return [i for i in lst if i != item]