"EmptyMethodsList" are generated during
method selection to indicate failed search (forcing backtracking).
Other classes described here are used internally in method dispatch.
All these are for internal use.## class described below
"EmptyMethodsList"### Other, virtual classes used in method dispatch
"OptionalMethods"
"PossibleMethod"
"EmptyMethodsList" in the
signature.MethodsListSelect (deprecated since Rversion
3.2.0) uses the objects;
class MethodsList is formally defunct since R3.2.0.