data Note ref
    = LinkNote URI
    | SeqNote (List ref)

instance functorNote :: Functor Note where
    map f (LinkNote uri) = LinkNote uri
    map f (SeqNote refs) = SeqNote (map f refs)

children :: forall ref. Note ref -> List ref
children (LinkNote _) = Nil
children (SeqNote refs) = refs

@mixin dgnote--note-indent($level) {
    text-indent: $level * $unit;
    @if $level <= 100 {
        > .-payload > .dgnote--note {
            @include dgnote--note-indent($level + 1);
        }
    }
}
.dgnote--note {
    @include dgnote--note-indent(1);
}