input: Write a function that takes a list of items and a specific item to be deleted. The function should remove the specified item from the list if it exists and return a message indicating success or failure.
  
  def delete_item(items, item):
      if item in items:
          items.remove(item)
          return "Item successfully deleted."
      else:
          return "Item not found."
  
  assert delete_item(["Apple", "Banana", "Orange"], "Banana") == "Item successfully deleted."
  assert delete_item(["Apple", "Banana", "Orange"], "Grapes") == "Item not found."
  assert delete_item(["Apple", "Banana", "Orange"], "Apple") == "Item successfully deleted."
  assert delete_item([], "Banana") == "Item not found."
  assert delete_item(["Apple", "Banana", "Orange"], "Orange") == "Item successfully deleted."
output: def delete_item(items, item):
      if item in items:
          items.remove(item)
          return "Item successfully deleted."
      else:
          return "Item not found."