code: def pop(self, count):
          
          if len(self._contexts) - 1 < count:
              _logger.error("#pop value is too big %d", len(self._contexts))
              if len(self._contexts) > 1:
                  return ContextStack(self._contexts[:1], self._data[:1])
              else:
                  return self
  
          return ContextStack(self._contexts[:-count], self._data[:-count])
docs: Returns new context stack, which doesn't contain few levels