code: func (v *MrbValue) SingletonClass() *Class {
  	mrb := &Mrb{v.state}
  	sclass := C._go_mrb_class_ptr(C.mrb_singleton_class(v.state, v.value))
  	return newClass(mrb, sclass)
  }
docs: // SingletonClass returns the singleton class (a class isolated just for the
  // scope of the object) for the given value.