input: Write a function to create a REST API in Python using Flask that can be used to delete an item from a list. If an item is successfully deleted, return a success message. If the item is not found, return an appropriate not found message.
  from flask import Flask, request
  import json
  
  app = Flask(__name__)
  items = ["Apple", "Banana", "Orange"]
  
  @app.route('/items', methods=["GET"])
  def get_items():
   return json.dumps(items)
  
  @app.route('/items/<item>', methods=["DELETE"])
  def delete_item(item):
   if item in items:
    items.remove(item)
    message = "Item successfully deleted."
   else:
    message = "Item not found."
   return json.dumps({"message": message})
  
  assert delete_item('Banana') == json.dumps({"message": "Item successfully deleted."})
  assert delete_item('Grape') == json.dumps({"message": "Item not found."})
output: if item in items:
      items.remove(item)
      message = "Item successfully deleted."
  else:
      message = "Item not found."
  return json.dumps({"message": message})