my %memoize;
foreach my $range (values %Build) {
   $message =~ s{ (\[ ([$range]+) \]) }{
      my $val = exists($memoize{$2}) ? $memoize{$2} : return_number("$2");
      $memoize{$2} = $val;
      defined($val) ? $val : $1
   }exig
}