https://cran.r-universe.dev/happytimehttps://cran.r-universe.dev/api/packages/happytimehttps://cran.r-universe.dev/happytime/happytime.pdfhttps://cran.r-universe.dev/happytime/doc/manual.htmlhttps://cran.r-universe.dev/happytime/citationhttps://cran.r-universe.dev/happytime/citation.txthttps://cran.r-universe.dev/happytime/citation.cff