bioc_version() queries the matching Bioconductor version for
an R version, defaulting to the current R version
bioc_version_map() returns the current mapping between R versions
and Bioconductor versions.
bioc_devel_version() returns the version number of the current
Bioconductor devel version.
bioc_release_version() returns the version number of the current
Bioconductor release.
bioc_repos() returns the Bioconductor repository URLs.
See the BioC_mirror option and the R_BIOC_MIRROR and
R_BIOC_VERSION environment variables in the pkgcache manual page.
They can be used to customize the desired Bioconductor version.