Retrieve Equity objects for a list of sids.

        Users generally shouldn't need to this method (instead, they should
        prefer the more general/friendly `retrieve_assets`), but it has a
        documented interface and tests because it's used upstream.

        Parameters
        ----------
        sids : iterable[string]

        Returns
        -------
        equities : dict[str -> Equity]

        Raises
        ------
        EquitiesNotFound
            When any requested asset isn't found.

def retrieve_equities(self, sids):
        """
        Retrieve Equity objects for a list of sids.

        Users generally shouldn't need to this method (instead, they should
        prefer the more general/friendly `retrieve_assets`), but it has a
        documented interface and tests because it's used upstream.

        Parameters
        ----------
        sids : iterable[string]

        Returns
        -------
        equities : dict[str -> Equity]

        Raises
        ------
        EquitiesNotFound
            When any requested asset isn't found.
        """
        cache = self._asset_cache

        try:
            return {
                k: cache[k]
                for k in sids
            }
        except KeyError:
            raise EquitiesNotFound(sids=sids)