def _validate_assets(self, assets):
        """Validate that asset identifiers are contained in the daily bars.

        Parameters
        ----------
        assets : array-like[int]
           The asset identifiers to validate.

        Raises
        ------
        NoDataForSid
            If one or more of the provided asset identifiers are not
            contained in the daily bars.
        """
        missing_sids = np.setdiff1d(assets, self.sids)

        if len(missing_sids):
            raise NoDataForSid(
                'Assets not contained in daily pricing file: {}'.format(
                    missing_sids
                )
            )