text: import flask 
  from flask import request, jsonify 
  from flask_cors import CORS
  
  
  '''
  Code Reference 
  https://programminghistorian.org/en/lessons/creating-apis-with-python-and-flask
  https://wings2pc.tistory.com/entry/%EC%9B%B9-%EC%95%B1%ED%94%84%EB%A1%9C%EA%B7%B8%EB%9E%98%EB%B0%8D-%ED%8C%8C%EC%9D%B4%EC%8D%AC-%ED%94%8C%EB%9D%BC%EC%8A%A4%ED%81%ACPython-Flask-Request-get-parameterHTTP-method-GET-POST
  
  '''
  app = flask.Flask(__name__)
  CORS(app)
  app.config["DEBUG"] = True
  
  
  
  @app.route('/', methods=['GET'])
  def home():
      return "<h1>Arithmetic is Fun!!</h1><p>You can do plus, minus, multiply, divide.</p>"
  
  
  @app.route('/plus', methods=['GET'])
  def plus():
      a = float(request.args["a"])
      b = float(request.args["b"])
      return jsonify({"ans" : a + b})
  
  @app.route('/minus', methods=['GET'])
  def minus():
      a = float(request.args["a"])
      b = float(request.args["b"])
      return jsonify({"ans" : a - b})
  
  @app.route('/multiply', methods=['GET'])
  def multiply():
      a = float(request.args["a"])
      b = float(request.args["b"])
      return jsonify({"ans" : a * b})
  
  @app.route('/divide', methods=['GET'])
  def divide():
      a = float(request.args["a"])
      b = float(request.args["b"])
      return jsonify({"ans" : a / b})
  
  if __name__ == "__main__":
     app.run(host='0.0.0.0', port=5000)
  