Delete the model with given identifier in the database. Returns the
        handle for the deleted model or None if object identifier is unknown.

        Parameters
        ----------
        identifier : string
            Unique model identifier
        erase : Boolean, optinal
            If true, the record will be deleted from the database. Otherwise,
            the active flag will be set to False to support provenance tracking.

        Returns
        -------
        ModelHandle

def delete_model(self, identifier, erase=False):
        """Delete the model with given identifier in the database. Returns the
        handle for the deleted model or None if object identifier is unknown.

        Parameters
        ----------
        identifier : string
            Unique model identifier
        erase : Boolean, optinal
            If true, the record will be deleted from the database. Otherwise,
            the active flag will be set to False to support provenance tracking.

        Returns
        -------
        ModelHandle
        """
        self.delete_object(identifier, erase=erase)