input: 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})
output:     
  @app.route('/items', methods=["POST"])
  def add_item():
      new_item = request.json.get('item')
      if new_item and new_item not in items:
          items.append(new_item)
          message = "Item successfully added."
      else:
          message = "Item already exists or is invalid."
      return json.dumps({"message": message})
  