code: func (r *PrefixedRegistry) GetOrRegister(name string, metric interface{}) interface{} {
  	realName := r.prefix + name
  	return r.underlying.GetOrRegister(realName, metric)
  }
docs: // Gets an existing metric or registers the given one.
  // The interface can be the metric to register if not found in registry,
  // or a function returning the metric for lazy instantiation.