input: from typing import List
  
  def delete_item(items: List[str], item_to_delete: str) -> str:
      """ Delete an item from the given list. If the item is found and deleted,
      return a string message indicating successful deletion. If the item is not
      found, return a string message indicating the item was not found.
      >>> delete_item(["Apple", "Banana", "Orange"], "Banana")
      'Item successfully deleted.'
      >>> delete_item(["Apple", "Banana", "Orange"], "Grapes")
      'Item not found.'
      """
output:     if item_to_delete in items:
          items.remove(item_to_delete)
          return 'Item successfully deleted.'
      else:
          return 'Item not found.'