code: func (p *Namespaces) CloneTo(p2 *Namespaces) {
  	if p == p2 {
  		return
  	}
  	if !p.Safe {
  		p.mu.RLock()
  		defer p.mu.RUnlock()
  	}
  	if !p2.Safe {
  		p2.mu.Lock()
  		defer p2.mu.Unlock()
  	}
  	if p2.prefixes == nil {
  		p2.prefixes = make(map[string]string, len(p.prefixes))
  	}
  	for pref, ns := range p.prefixes {
  		p2.prefixes[pref] = ns
  	}
  }
docs: // CloneTo adds registered namespaces to a given list.