import { popup_filter_yesno } from "https://deno.land/x/denops_std@v6.5.0/function/vim/mod.ts";
Filter that can be used for a popup. It handles only the keys
'y', 'Y' and 'n' or 'N'. Invokes the "callback" of the
popup menu with the 1 for 'y' or 'Y' and zero for 'n' or 'N'
as the second argument. Pressing Esc and 'x' works like
pressing 'n'. CTRL-C invokes the callback with -1. Other
keys are ignored.
See the example here: popup_dialog-example