sub new
{
    # object creation
	my $class = shift;
	my $self = { };
	bless ($self, $class);

    # session creation
    POE::Session -> create(
        object_states =>
            [
                $self =>
                    {
                        _start          => 'client_start',
                    },
            ],
    );
    return $self;
}

sub client_start
{
    # this is an overwritten method!!!
    my ($self, $kernel, $heap, $session) = @_[ OBJECT, KERNEL, HEAP, SESSION ];
    # child code goes here
    # [...]
    # now, access the overwritten parent method
    $self -> SUPER::client_start( @_ );
}