https://chedgala.r-universe.dev/Opportunistichttps://chedgala.r-universe.dev/api/packages/Opportunistichttps://chedgala.r-universe.dev/Opportunistic/Opportunistic.pdfhttps://chedgala.r-universe.dev/Opportunistic/doc/manual.htmlhttps://chedgala.r-universe.dev/Opportunistic/citationhttps://chedgala.r-universe.dev/Opportunistic/citation.txthttps://chedgala.r-universe.dev/Opportunistic/citation.cff