code: public CallTreeNode addChild(String name) {
  		if (children == null) {
  			children = new HashMap<>();
  		}
  		CallTreeNode child = new CallTreeNode(name);
  		children.put(name, child);
  		child.parent = this;
  		return child;
  	}
docs: Adds a child to this tree node.
  
  @param name Child Simon name
  @return Created child node