code: def _validate_dtype(self, dtype):
          
  
          if dtype is not None:
              dtype = pandas_dtype(dtype)
  
              # a compound dtype
              if dtype.kind == 'V':
                  raise NotImplementedError("compound dtypes are not implemented"
                                            " in the {0} constructor"
                                            .format(self.__class__.__name__))
  
          return dtype
docs: validate the passed dtype