function getopts -d "Parse CLI options"
    if not set -q argv[1]
        return 1
    end

    printf "%s\n" $argv | sed -E '
        s/^-([A-Za-z]+)/- \1 /
        s/^--([A-Za-z0-9_-]+)(!?)=?(.*)/-- \1 \3 \2 /' | \
    awk '
        function add(k, v)  { if (seen[k v]++) return; print k (v == "" ? "" : " "v) }
        function pop()      { return size <= 0 ? "_" : stack[size--] }
        function push(k)    { stack[++size] = k }
        function flush()    { while (size) add(pop()) }

        $0 == "" { next }
        done     { add("_" , $1$2$3); next }

        $1 == "--" && !$2   { done = 1            ; next }
        $1 !~ /^-|^--/      { add( pop(), $0 )    ; next }

        size { flush() }
        $3   { for (i = 4; i <= NF; i++) $3 = $3" "$i }

        $1 == "--" { if ($3 == "") push($2); else add($2, $3) }
        $1 == "-" {
          if ($2 == "") { print $1; next } else n = split($2, keys, "")
          if ($3 == "") push(keys[n]); else add(keys[n], $3)
          for (i = 1; i < n; i++) add(keys[i])
        }

        END { flush() }
    '
end