These functions can be used as convenient shortcuts
for the repos argument to e.g. do_package_checks() and
step_install_deps().
repo_default() returns the value of the "repos" option,
or repo_cloud() if the option is not set.
repo_cloud() returns RStudio's CRAN mirror.
repo_cran() returns the master CRAN repo.
repo_bioc() returns Bioconductor repos from
remotes::bioc_install_repos(), in addition to the default repo.
repo_default()repo_cloud()
repo_cran()
repo_bioc(base = repo_default())
The base repo to use, defaults to repo_default().
Pass NULL to install only from Bioconductor repos.