input: Write a function to create a basic REST API using Python and Flask to list all the countries in the world. The API should read the list of countries from a JSON file and return them as a JSON response.
  assert create_rest_api() == """
  import flask
  from flask import Flask, request, jsonify
  import json
  
  app = Flask(name)
  
  @app.route('/countries', methods=['GET'])
  def get_countries():
      with open('data.json', 'r') as f:
          countries = json.load(f)
      return jsonify(countries)
  
  if name == 'main':
      app.run()"""
  assert create_rest_api() != """""
  assert create_rest_api() != None
output: 
  import flask
  from flask import Flask, request, jsonify
  import json
  
  app = Flask(__name__)
  
  @app.route('/countries', methods=['GET'])
  def get_countries():
      with open('data.json', 'r') as f:
          countries = json.load(f)
      return jsonify(countries)
  
  if __name__ == '__main__':
      app.run()
  