code: def setattr(d, **kwarg):
          
          if _meta not in d:
              d[_meta] = dict()
          for k, v in kwarg.items():
              d[_meta][k] = v
docs: Set an attribute.
  
          set attributes is actually add a special key, value pair in this dict
          under key = "_meta".
  
          Usage::
  
              >>> DT.setattr(d, population=27800000)
              >>> d
              {'_meta': {'population': 27800000, '_rootname': 'US'}}