sub addtwo {
        #shift the first value from @_, the argument list of the subroutine
        #shift() is a built in Perl subroutine that takes an array as an argument, then returns and
        #deletes the first item in that array.
    my $params = shift;
        #set a variable 's' to be a shift of the $structure variable
    my $s = $params {$structure};


    #if 's' has a datatype of LIST
    if (ref($s) eq "LIST") {
         $c = 0;
        foreach my $e (@{$s}) {
            $s->[$c] = addtwo({ structures => $e });
             #"->" is an infix dereference operator, just as it is in C and C++.
         #If the right side is either a [...], {...}, or a (...) subscript, then the left side
                 #must be either a hard or symbolic reference to an array, a hash, or a subroutine
         #respectively. (Or technically speaking, a location capable of holding a hard reference,
         #if it's an array or hash reference being used for assignment.)
            $c++;
        }
    } elsif (ref($s) eq "HASH") {

        if (scalar keys %{$s} == 0) {
            return undef;
       } else {
            foreach my $e (values %{$s}) {
                $s{$e} = addtwo({ structure => $s->{$e} });
            }
        }

    } else {
        $s = 1;
    }

    return $c;
}