sub odds_up_to {
        my $maximum = shift;
        seq( 1 .. $maximum )
            ->seq_filter( sub { $_[0] % 2 } )
    }

    enumerate( odds_up_to(10) );

    #  0 => 1
    #  1 => 3
    #  2 => 5
    #  3 => 7
    #  4 => 9