docs: def delete(self, criteria=None, _all=False):
          ''' delete dictionary(ies) in sqlite database
  
          _all = True - delete all items
          '''
          if isinstance(criteria, self._item_class):
              criteria = {'_id': criteria['_id']}
  
          if criteria is None and not _all:
              raise RuntimeError('Criteria is not defined')
  
          SQL = SQLBuilder(self._table, criteria).delete()
          self._cursor.execute(SQL)