I've set the mapping keys as follows:

```
" Easy indent for code blocks
  nmap <tab>      v>
  nmap <s-tab>    v<
  vmap <tab>      >gv
  vmap <s-tab>    <gv

```

That works good. But, when I installed `UltiSnips` by vundle, the Tab key does't work as indent action, it will remove multi-line codes which I selected. I know this is because the default setting of `UltiSnips`. I would like to remain the Tab mapping for `UltiSnips` to trigger its functions, How do I solve the problem of using the TAB key to indent code blocks? Thanks!