code: def is_restricted(self, assets, dt):
          
          if isinstance(assets, Asset):
              return self._is_restricted_for_asset(assets, dt)
  
          is_restricted = partial(self._is_restricted_for_asset, dt=dt)
          return pd.Series(
              index=pd.Index(assets),
              data=vectorize(is_restricted, otypes=[bool])(assets)
          )
docs: Returns whether or not an asset or iterable of assets is restricted
          on a dt.