'Unassign a volume from a host/hostgroup.'

def unassign(self, vol_name, host_name=None, hostgroup_name=None):

    cmd = RdxApiCmd(cmd_prefix=[VOLUMES, 'unassign'])
    cmd.set_argument(vol_name)
    cmd.add_flag('host', host_name)
    cmd.add_flag('group', hostgroup_name)
    return self._run_cmd(cmd)
