protected function addChild (ContextInterface $child)
	{
		$length = count($this->stack);
		$this->stack[$length-1]->addChild ($child);
	}
protected function addChild (ContextInterface $child)
	{
		$length = count($this->stack);
		$this->stack[$length-1]->addChild ($child);
	}
protected function addChild ( ContextInterface $ child ) { $ length = count ( $ this -> stack ) ; $ this -> stack [ $ length - 1 ] -> addChild ( $ child ) ; }
Add a child to current context
@param ContextInterface $child
@return void
Add a child to current context