Change storage medium in this VM.

        :param params: params to use with sub-command storageattach

def _storage_attach(self, params):
        """
        Change storage medium in this VM.

        :param params: params to use with sub-command storageattach
        """

        args = shlex.split(params)
        yield from self.manager.execute("storageattach", [self._vmname] + args)