input: Write a python function to check if an element exists in a list.
  assert item_exists([1, 2, 3, 4, 5], 3) == True
  assert item_exists([1, 2, 3, 4, 5], 6) == False
  assert item_exists(['apple', 'banana', 'cherry'], 'banana') == True
  assert item_exists(['apple', 'banana', 'cherry'], 'orange') == False
output: def item_exists(lst, element):
      return element in lst