Select Code to Download

if (valid_state($pull_downs) && $start_time < $end_time) {
    # okay; put processing here
} else {
    # not okay: yell at user.
}

# put this before the if mentioned above
my $pull_downs = join "", $pull_down1, $pull_down2, $pull_down3, $pull
+_down4;

...
    return shift =~ $valid;
  |
}