v0.2.4.3 revise __um_main()
v0.2.4.4 revise __um_main(), __um_edit() and __um_rebuild_index()
v0.2.5.0 revise __um_edit()
v0.2.5.0 revise __um_edit()
v0.2.5.0 revise __um_edit()
v0.2.5.1 revise __um_delete()
v0.2.5.2 revise __um_modify()