code: def file_id_to_name(self, file_id):
          
          sql = 'select name from files where id = ?'
          logging.debug('%s %s', sql, (file_id,))
          self.cursor.execute(sql, (file_id,))
          name = self.cursor.fetchone()
          if name:
              return name[0]
          return ''
docs: Convert a file id to the file name.