code: def get_item(self, url):
          
  
          _hash = self.build_hash(url)
          self.cursor.execute('BEGIN')
          sql = '''
                SELECT data
                FROM cache
                WHERE id = %s
            '''
          self.cursor.execute(sql, (_hash,))
          row = self.cursor.fetchone()
          self.cursor.execute('COMMIT')
          if row:
              data = row[0]
              return self.unpack_database_value(data)
          else:
              return None
docs: Returned item should have specific interface. See module docstring.