Delete a named snapshot

        Parameters
        ----------
        symbol : `str`
            The snapshot name to delete

def delete_snapshot(self, snap_name):
        """
        Delete a named snapshot

        Parameters
        ----------
        symbol : `str`
            The snapshot name to delete
        """
        snapshot = self._snapshots.find_one({'name': snap_name})
        if not snapshot:
            raise NoDataFoundException("Snapshot %s not found!" % snap_name)

        # Remove the snapshot Id as a parent of versions
        self._versions.update_many({'parent': snapshot['_id']},
                                   {'$pull': {'parent': snapshot['_id']}})

        self._snapshots.delete_one({'name': snap_name})