環境 Windows 10 64bit Python 3.8.3 Flask 1.1.1 フォルダ構成 ├ app.py └ templates/ ├ login.html ├ welcome.html └ contents.html コードの中身 app.py from flask import Flask, request, redirect, render_template, flash, session app = Flask(__name__) app.config[‘SECRET_KEY’] = ‘secret_key’ app.config[‘USERNAME’] = ‘user’ app.config[‘PASSWORD’] = ‘pass’ @app.route(‘/’) def index(): if “flag” in session and session[“fla