Construct a feature set from features available in currently loaded packages. Lists of available features can be found in the following pages:
feature_set(pkgs = NULL, tags = NULL)Features can be registered for use with the feature_set() function using
register_feature(). This function allows you to register a feature along
with the tags associated with it. If the features are being registered from
within a package, this feature registration should happen at load time using
[.onLoad()].