Usage
in_dir(new, code)with_collate(new, code)
with_envvar(new, code, action = "replace")
with_lib(new, code)
with_libpaths(new, code)
with_locale(new, code)
with_makevars(new, code, path = file.path("~", ".R", "Makevars"))
with_options(new, code)
with_par(new, code)
with_path(new, code, add = TRUE)