code: func (p *pathTree) has(rel string) bool {
  	if p == nil {
  		return false
  	}
  
  	if !p.caseSensitive {
  		rel = strings.ToLower(rel)
  	}
  
  	// It matches some added entry exactly?
  	if p.leafs.Has(rel) {
  		return true
  	}
  	// Was added as a parent of some entry?
  	if p.nodes.Has(rel) {
  		return true
  	}
  
  	// Maybe it has some added entry as its parent?
  	found := false
  	parentDirs(rel, func(par string) bool {
  		found = p.leafs.Has(par)
  		return !found
  	})
  	return found
  }
docs: // has returns true if a native path 'rel' is in the tree.
  //
  // nil pathTree is considered empty.