code: func (h *Handle) ClassAdd(class Class) error {
  	return h.classModify(
  		unix.RTM_NEWTCLASS,
  		unix.NLM_F_CREATE|unix.NLM_F_EXCL,
  		class,
  	)
  }
docs: // ClassAdd will add a class to the system.
  // Equivalent to: `tc class add $class`