Pinq\Queryable::getSource PHP Method

    public function getSource()
    {
        if ($this->isSource()) {
            return $this;
        } else {
            $expression = $this->expression;
            while ($expression instanceof O\TraversalExpression) {
                $expression = $expression->getValue();
            }
            if ($expression instanceof O\ValueExpression) {
                return $expression->getValue();
            } else {
                throw new PinqException('Invalid origin expression: must be instance of %s', O\ValueExpression::getType());
            }
        }
    }