input: Write a function to create a REST API in Python using Flask that provides endpoints to delete an item from a list. The list starts with items "Apple", "Banana", and "Orange". The API should have a GET endpoint to retrieve the list of items and a DELETE endpoint to remove a specific item from the list. If the item is successfully deleted, return a success message; otherwise, return an error message indicating the item was not found.
  
  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")=="{\"message\": \"Item successfully deleted.\"}"
  assert delete_item("Orange")=="{\"message\": \"Item successfully deleted.\"}"
  assert delete_item("Apple")=="{\"message\": \"Item successfully deleted.\"}"
  assert delete_item("Grapes")=="{\"message\": \"Item not found.\"}"
output: 
  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})
  