True when a fetched document is an IIIF Presentation 3 manifest (accepted directly as a StoryMap source).
Converts a IIIF Presentation API 3.0 manifest into legacy StoryMapJS data (the storymap object). Malformed or missing pieces are skipped; the result always contains at least {slides: []}.
storymap
{slides: []}
True when a fetched document is an IIIF Presentation 3 manifest (accepted directly as a StoryMap source).