code: def enterexp():
      
      app.logger.info("Accessing /inexp")
      if not 'uniqueId' in request.form:
          raise ExperimentError('improper_inputs')
      unique_id = request.form['uniqueId']
  
      try:
          user = Participant.query.\
              filter(Participant.uniqueid == unique_id).one()
          user.status = STARTED
          user.beginexp = datetime.datetime.now()
          db_session.add(user)
          db_session.commit()
          resp = {"status": "success"}
      except exc.SQLAlchemyError:
          app.logger.error("DB error: Unique user not found.")
          resp = {"status": "error, uniqueId not found"}
      return jsonify(**resp)
docs: AJAX listener that listens for a signal from the user's script when they
      leave the instructions and enter the real experiment. After the server
      receives this signal, it will no longer allow them to re-access the
      experiment applet (meaning they can't do part of the experiment and
      referesh to start over).