Rather than defining singleton methods like this, this feels like something that could be delegated to metadata (similar to `described_class` and `file_path`:

https://github.com/rspec/rspec-core/blob/505939b342037e09ae3a552f3d7adb217660b8ad/lib/rspec/core/example_group.rb#L49

Thoughts?

Also, the `singleton_class.send(:define_method, :order) { parent.order }` bit seems very odd to me; won't ruby's method dispatch cause it to use the parent class's implementation already, w/o a need to explicitly define it to delegate to the parent?