code: public function compile(Twig_NodeInterface $node, $indentation = 0)
      {
          $this->lastLine = null;
          $this->source = '';
          $this->debugInfo = array();
          $this->sourceOffset = 0;
          // source code starts at 1 (as we then increment it when we encounter new lines)
          $this->sourceLine = 1;
          $this->indentation = $indentation;
          $this->varNameSalt = 0;
  
          if ($node instanceof Twig_Node_Module) {
              // to be removed in 2.0
              $this->filename = $node->getTemplateName();
          }
  
          $node->compile($this);
  
          return $this;
      }
docs: Compiles a node.
  
  @param Twig_NodeInterface $node        The node to compile
  @param int                $indentation The current indentation
  
  @return $this