code: def get_pub_id_owner(self, pub_id):
          
          con = self.connection or self._connect()
          cur = con.cursor()
  
          cur.execute(
              """SELECT distinct username from upload.reaction
              WHERE pub_id = '{pub_id}'"""
              .format(pub_id=pub_id))
  
          username = cur.fetchall()[0][0]
  
          return username
docs: Check if a user owns a publication