Creating a Seq from a List of Seqs

gistfile1.txt

sub ListOfSeqsToSeq(**@seqs) {
    Seq.new( class :: does Iterator {
        has @.seqs;
        has $!iterator;
        method TWEAK() { $!iterator = @!seqs.shift.iterator if @!seqs }
        method pull-one() is raw {
            if $!iterator {
                my $pulled := $!iterator.pull-one;
                if $pulled =:= IterationEnd {
                    if @!seqs {
                        $!iterator = @!seqs.shift.iterator;
                        $pulled := self.pull-one;
                    }
                    else {
                        $!iterator = Nil;
                    }
                }
                $pulled
            }
            else {
                IterationEnd
            }
        }
    }.new( :@seqs ) )
}

dd ListOfSeqsToSeq( Seq.new((1,2,3).iterator), (Seq.new((4,5,6).iterator) ) )