6 has over => (is => 'ro', required => 1);
8 has values => (is => 'ro', default => sub { {} });
12 my $values = $self->values;
13 return DX::ArrayStream->from_array(@{$values}{sort keys %$values});
17 my ($self, $value) = @_;
18 return ref($self)->new(
20 values => { %{$self->values}, $value->${\$self->over} => $value }