module T::Private::Methods

def self.signature_for_key(key)
_for_key(key)
 inherits a method `foo` from Base, then
od(:foo) != Base.instance_method(:foo) even though they resolve to the
larly, Foo.method(:bar) != Foo.singleton_class.instance_method(:bar).
the look up by the method on the owner (Base in this example).
od[key]