Subclasses of BasicObject are rare in general, but pretty common in testing/mocking frameworks.

Today, the logic in print_variable will raise NoMethodError for such objects, and always hit this rescue:

You can see this other PR of mine to see what's involved, but in short:

1. Replacing object.is_a?(Foo) with Foo === object
2. Replacing object.to_s with Kernel.instance_method(:to_s).bind_call(object)

Before I try this, would this be a welcome contribution to merge?