%wordBank = (
NOUN => "kangaroo",
ADVERB => "far",
)

##</code><code>##

#!/usr/bin/perl -w
  use strict;
  sub safeReplace {
    my($hashkey,%hash) = @_;
    my $hash = \%hash;  
    my $retval = '';
    if (defined($hash{$hashkey})) {
      $retval = $hash{$hashkey};
    }  else {
      $retval = "\%$hashkey\%";
    }
    return $retval;
  }

  sub preProcessStr {
    my($string,%options) = @_;
    $string =~ s/%(.+?)%/safeReplace($1,%options)/ge;
    return $string;
  }
  
  my  %options = (
              ARG1 => "test",
              ARG2 => "123...",
             );
  my $string = 'Hello %ARG1%, counting down %ARG2% .. %NOT%';
  
  $string = preProcessStr($string,%options);
  print "$string\n"