sub days
  {
  my ($then) = shift;
  my $seconds = time - $then;
  my $minutes = int ($seconds / 60);
  my $hours = int ($minutes / 60);
  my $days = int ($hours / 24);

  if ($seconds < 60)
    { return (sprintf "%d second%s", $seconds, $seconds == 1 ? "" : "s"); }
  elsif ($minutes < 60)
    { return (sprintf "%d minute%s", $minutes, $minutes == 1 ? "" : "s"); }
  elsif ($hours < 24)
    { return (sprintf "%d hour%s", $hours, $hours == 1 ? "" : "s"); }
  else
    { return (sprintf "%s day%s", &commas ($days), $days == 1 ? "" : "s"); }
  }