https://opensafely-core.r-universe.dev/dd4dhttps://opensafely-core.r-universe.dev/api/packages/dd4dhttps://opensafely-core.r-universe.dev/dd4d/dd4d.pdfhttps://opensafely-core.r-universe.dev/dd4d/doc/manual.htmlhttps://opensafely-core.r-universe.dev/dd4d/citationhttps://opensafely-core.r-universe.dev/dd4d/citation.txthttps://opensafely-core.r-universe.dev/dd4d/citation.cff