input: Write a python function to manage a grocery list by adding, displaying, and deleting items.
  assert manage_grocery_list(['add', 'eggs'], []) == ['eggs']
  assert manage_grocery_list(['add', 'milk', 'add', 'bread', 'delete', 'milk', 'display'], []) == ['bread']
  assert manage_grocery_list(['add', 'apples', 'add', 'oranges', 'delete', 'bananas'], ['apples', 'oranges']) == ['apples', 'oranges']
output: def manage_grocery_list(actions, initial_list):
      grocery_list = initial_list[:]
      i = 0
      while i < len(actions):
          action = actions[i]
          if action == 'add':
              i += 1
              item = actions[i]
              grocery_list.append(item)
          elif action == 'delete':
              i += 1
              item = actions[i]
              if item in grocery_list:
                  grocery_list.remove(item)
          elif action == 'display':
              return grocery_list
          i += 1
      return grocery_list