Returns HTML navigation element with unordered list of links.
If optional array mask is passed, anchors are added according to
their mask state.
| Type | Intent | Optional | Attributes | Name | ||
|---|---|---|---|---|---|---|
| type(anchor_type), | intent(inout) | :: | anchors(:) | Anchor types. | ||
| logical, | intent(inout), | optional | :: | mask(:) | Mask. | 
Generated HTML.