def METHOD_NAME(number_of_pages, force=False, cache_flag=False):
    mets = OcrdMets.empty_mets(cache_flag=cache_flag)
    mets._number_of_pages = number_of_pages
    for n in ['%04d' % (n + 1) for n in range(number_of_pages)]:
        _add_file = lambda n, fileGrp, mimetype, ID=None: mets.add_file(
            fileGrp,
            mimetype=mimetype,
            pageId='PHYS_%s' % n,
            ID=ID if ID else '%s_%s_%s' % (fileGrp, n, MIME_TO_EXT.get(mimetype)[1:].upper()),
            url='%s/%s%s' % (fileGrp, ID if ID else '%s_%s_%s' % (fileGrp, n, MIME_TO_EXT.get(mimetype)[1:].upper()), MIME_TO_EXT.get(mimetype))
        )
        for grp in GRPS_IMG:
            # LINES_PER_REGION = 2
            _add_file(n, grp, 'image/tiff')
            _add_file(n, grp, 'application/vnd.prima.page+xml')
        for grp in GRPS_REG:
            # REGIONS_PER_PAGE = 10
            for region_n in range(REGIONS_PER_PAGE):
                _add_file(n, grp, 'image/png', '%s_%s_region%s' % (grp, n, region_n))
    return mets