from flask import Flask, session

@app.route('/my-route')
def my_route():
  id = request.args.get('id')
  schema = Schema({
    Required('id'): All(Coerce(str))
})
try:
    schema({'id': id})
except MultipleInvalid as e:
    str(e)

  ans=test(session[‘id’])
  return ans

if __name__ == '__main__':

    app.secret_key = 'super secret key'
    app.config['SESSION_TYPE'] = 'filesystem'

    sess.init_app(app)

    app.debug = True

    app.run()