code: public void add(DepTreeNode child) {
  		if (children == null) {
  			children = new HashMap<String, DepTreeNode>();
  		}
  		children.put(child.getName(), child);
  		child.setParent(this);
  	}
docs: Add the specified node to this node's children.
  
  @param child
  The node to add to this node's children