old_contents: from session import RedisSessionInterface
  from flask import Flask, render_template, request, session, url_for, \
                    redirect, jsonify
  from uuid import uuid4
  from chat import get_conversation, send_message as do_chat, is_valid_chatroom
  
  app = Flask(__name__)
  
  @app.route('/')
  def index():
      return render_template('index.html')
  
  @app.route('/user/login', methods=['POST'])
  def login():
      username = request.form.get('username', '').strip()
      if len(username) == 0:
          return redirect(url_for('index'))
      session['user'] = {
          'user.id': str(uuid4()),
          'name': username
      }
      return redirect(url_for('chat'))
  
  @app.route('/user/logout')
  def logout():
      session.pop('user', None)
      return redirect(url_for('index'))
  
  @app.route('/chat/{chatroom}')
  def chat(chatroom=None):
      if not is_valid_chatroom(chatroom) or session.get('user') is None:
          return redirect(url_for('index'))
      log = get_conversation(chatroom)
      if log is None:
          return redirect(url_for('index'))
      return render_template('chat.html')
  
  @app.route('/chat/{chatroom}/message', methods=['POST'])
  def send_message(chatroom=None):
      message = request.json.get('message', '').strip()
      user = session.get('user', {})
      user_id = user.get('user.id')
      user_name = user.get('name')
      if not is_valid_chatroom(chatroom) or len(message) == 0 or \
         user_id is None or user_name is None:
          return jsonify(success=False)
      do_chat(user_id, user_name, message)
      return jsonify(success=True)
  
  if __name__ == '__main__':
      app.session_interface = RedisSessionInterface()
      app.run(debug=True)
  
  
new_contents: from session import RedisSessionInterface
  from flask import Flask, render_template, request, session, url_for, \
                    redirect, jsonify
  from uuid import uuid4
  from chat import get_conversation, send_message as do_chat, is_valid_chatroom
  
  app = Flask(__name__)
  
  @app.route('/')
  def index():
      return render_template('index.html')
  
  @app.route('/user/login', methods=['POST'])
  def login():
      username = request.form.get('username', '').strip()
      if len(username) == 0:
          return redirect(url_for('index'))
      session['user'] = {
          'user.id': str(uuid4()),
          'name': username
      }
      return redirect(url_for('chat'))
  
  @app.route('/user/logout')
  def logout():
      session.pop('user', None)
      return redirect(url_for('index'))
  
  @app.route('/chat/<chatroom>')
  def chat(chatroom=None):
      if not is_valid_chatroom(chatroom) or session.get('user') is None:
          return redirect(url_for('index'))
      log = get_conversation(chatroom)
      if log is None:
          return redirect(url_for('index'))
      return render_template('chat.html')
  
  @app.route('/chat/<chatroom>/message', methods=['POST'])
  def send_message(chatroom=None):
      message = request.json.get('message', '').strip()
      user = session.get('user', {})
      user_id = user.get('user.id')
      user_name = user.get('name')
      if not is_valid_chatroom(chatroom) or len(message) == 0 or \
         user_id is None or user_name is None:
          return jsonify(success=False)
      do_chat(user_id, user_name, message)
      return jsonify(success=True)
  
  if __name__ == '__main__':
      app.session_interface = RedisSessionInterface()
      app.run(debug=True)
  
  
subject: Correct routing syntax