vim9script

const Sep = "₀◎○ë" # something that won't be met anywhere

export def Do(first: number, last: number, sep: string)
    var in: list<string>
    for n in range(first, last)
        in = add(in, substitute(getline(n), sep, "\t" .. Sep, "g"))
    endfor
    var out = systemlist("column -t -s \"\t\"", add(in, ""))
    for n in range(first, last)
        setline(n, substitute(out[n - first], "  " .. Sep, escape(sep, "&"), "g"))
    endfor
enddef