fn new_line(current_line: &mut String, out: &mut String) {
    out.push('\n');
    out.push_str(current_line);
    current_line.truncate(0);
}
// Append a newline and the current line to the output,
// clearing the current line.
Append a newline and the current line to the output,
clearing the current line.
Append a newline and the current line to the output clearing the current line .
fn new_line(current_line: &mut String, out: &mut String) {
    out.push('\n');
    out.push_str(current_line);
    current_line.truncate(0);
}
fn new_line ( current_line : & mut String , out : & mut String ) { out . push ( '\n' ) ; out . push_str ( current_line ) ; current_line . truncate ( 0 ) ; }
Append a newline and the current line to the output,
clearing the current line.
Append a newline and the current line to the output clearing the current line .
current_line
&mut String
out
&mut String
current_line
&mut String
out
&mut String