docs: def get_comments_by_userid(self, userid):
          """ Get comments record.
          output should be like: {'k1': 'v1', 'k2': 'v2'}'
          """
          userid = userid
          with get_guest_conn() as conn:
              res = conn.execute("SELECT comments FROM guests "
                                 "WHERE userid=?", (userid,))
  
          result = res.fetchall()
          comments = {}
          if result[0][0]:
              comments = json.loads(result[0][0])
          return comments