def __setattr__(self, key, value):
     if hasattr(self, '_fields') and key in self._fields:
         self[key] = value
     else:
         return Document.__setattr__(self, key, value)
 def __setattr__(self, key, value):
     if hasattr(self, '_fields') and key in self._fields:
         self[key] = value
     else:
         return Document.__setattr__(self, key, value)