display modified buffer info column for ddu.vim
display icon for file related to modified buffer
in the image bellow, the modified icon is "●".

https://github.com/vim-denops/denops.vim
https://github.com/Shougo/ddu.vim
call ddu#custom#patch_global(#{
\ columns: ['filename', 'file_buf_modified'],
\ })