(* tab p; *)
function printable(ch : char) : boolean;

begin
    if ch in (.' '..'~'.) then
        printable := true
    else
        printable := false
end;
function nextch(line_image : line;var count : integer) : char;

begin
    nextch := line_image(.count.);
    count := count + 1;
end;

procedure get_line(var line_image : line;var count : integer);

var ch : char;
    index : integer;

begin
    index := 1;
    repeat
        ch := inbt(log_unit);
        line_image(.index.) := ch;
        index := index +1;
    until ch = chr(lf);
    count := 1;
end;

procedure skip_until_number(var line_image: line;var count : integer);

begin
    repeat
        get_line(line_image,count);
    until line_image(.1.) in (.'0'..'9'.);
end;

procedure print_line(line_image : line);

var index : integer;
    ch    : char;

begin
    index := 1;
    repeat
        ch := line_image(.index.);
        outbt(1,ch);
        index := index +1;
    until ch = chr(lf);
end;

procedure back_wind(line_image : line;var count : integer);

begin
    count := count - 1;
    if count = 0 then
        halt('ERROR : not possible to backwind 1');
end;