https://wonderwall.hatenablog.com/entry/2016/03/26/211710 左の方
https://vim-jp.org/vimdoc-ja/sign.html
[* colorscheme]
:highlight SignColumn guibg=darkgrey
[* define] code:.vim :sign define piet text=>> texthl=Search
[* place] code:.vim :exe ":sign place 2 line=23 name=piet file=" . expand("%:p")
[* place] code:.vim :sign unplace 2