input: Write a function to create a REST API in Python using Flask that can be used to delete an item from a list, and return a message indicating success or failure.
  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 test_delete_item("Apple")=="Item successfully deleted."
  assert test_delete_item("Mango")=="Item not found."
  assert test_delete_item("Banana")=="Item successfully deleted."
  assert test_delete_item("Orange")=="Item successfully deleted."
output: 
  if item in items:
   items.remove(item)
   message = "Item successfully deleted."
  else:
   message = "Item not found."
  return json.dumps({"message": message})
  