ultisnips source for ddc.vim
https://github.com/vim-denops/denops.vim
https://github.com/Shougo/ddc.vim
https://github.com/SirVer/ultisnips
call ddc#custom#patch_global('sources', ['ultisnips'])
call ddc#custom#patch_global('sourceOptions', {
\ '_': {'matchers': ['matcher_head']},
\ 'ultisnips': {'mark': 'US'},
\ })
https://github.com/SirVer/ultisnips/blob/master/rplugin/python3/deoplete/sources/ultisnips.py