sub modify_query_str
{
#takes the parameter you wish to modify and the value you wish to set it to.
	return $ENV{'QUERY_STRING'} unless(scalar @_ == 2);
	my ($key, $value) = @_;
#Below is the substitution used in CGI::Util for the escape function.
	$value =~ s/([^a-zA-Z0-9_.-])/uc sprintf("%%%02x",ord($1))/eg; 
	my %values = map{split /=/,$_;} split /&/, $ENV{'QUERY_STRING'};
	$values{$key} = $value;
	return join("&", map{"$_=$values{$_}"}keys %values);		
}