use composition LWP::UserAgent             => 
                LWP::UserAgent::Determined => 
                LWP::UserAgent::Cached     => 
                LWP::UserAgent::Super;
use strict;

sub print_isa {
	my ($pkg, $level) = @_;
	
	print "\t"x$level, $pkg, "\n";
	
	no strict 'refs';
	for my $parent (@{"$pkg\::ISA"}) {
		print_isa($parent, $level+1);
	}
}

print_isa('LWP::UserAgent::Super');