Pinq\Expressions\ExpressionWalker::doWalk PHP Method

    protected function doWalk(Expression $expression)
    {
        return $expression->traverse($this);
    }

 protected function doWalk(O\Expression $expression)
 {
     if ($this->processor->matches($this->function, $expression)) {
         $processParameterCallback = $this->processParameterCallback;
         $expression = $processParameterCallback($this->processor, $expression);
     }
     return parent::doWalk($expression);
 }