chooseBioCmirror(graphics = getOption("menu.graphics"), ind = NULL,
useHTTPS = getOption("useHTTPS", TRUE),
local.only = FALSE)menu.chooseCRANmirror).options("BioC_mirror")."BioC_mirror": it is used
before a call to setRepositories. The out-of-the-box
default for that option is NULL, which currently corresponds to
the mirror https://bioconductor.org. The ‘Bioconductor (World-wide)’ ‘mirror’ is a network of
mirrors providing reliable world-wide access; other mirrors may
provide faster access on a geographically local scale. ind chooses a row in
R_HOME/doc/BioC_mirrors.csv,
by number.setRepositories, chooseCRANmirror.