5 has id => (is => 'ro', required => 1);
7 has bound_stream => (is => 'ro');
9 has bound_value => (is => 'lazy', clearer => 1, builder => sub {
10 $_[0]->bound_stream->next;
14 my ($self, $stream) = @_;
15 $self->new(%$self, bound_stream => $stream);