def _get_pdf_collection_type(coll) -> str:
    if len(coll) == 1 and len(coll[0]) == 1:
        return "SINGLE_PDF_SINGLE_PAGE"
    if len(coll) == 1 and len(coll[0]) > 1:
        return "SINGLE_PDF_MULTI_PAGE"
    if len(coll) > 1:
        for c in coll:
            if len(c) > 1:
                return "MULTI_PDF_MULTI_PAGE"
    return "MULTI_PDF_SINGLE_PAGE"