#!/usr/bin/perl
use strict;
use warnings;
use CGI;

# this is by default in package main scope

package TempConverter;

# define necessary stuff for TempConverter
# and start its package scope

# you can even do this, to....
package CGI;
# ...extend the CGI package, but this is not
# recommended

package TempConverter;
# back in TempConverter scope and add
# something you need

package main;
# now in main scope, ready for action!
# the safest place to do things