package top;
use Moose::Role;
requires    'token';
sub foo {
    print "foo\n";
}

package bottom;
use Moose::Role;
with 'top'  => {
                   -alias       =>{ foo  => '_foo', },
                   -excludes    => [ 'foo' ],
                 };

sub foo {
    print "bar\n";
}

package something;
use Moose;
with "bottom";

sub token {
    print "I don't want to implement token untill the concerete class but I want to use bottom's version of foo\n";
}

package main;
my $something = new something;
$something->foo;