code: public function convert(Expr\AssignRef $node)
      {
          $this->logger->logIncompatibility(
              '(=&) AssignRef',
              '(=&) AssignRef does not exist in zephir, assign',
              $node,
              $this->dispatcher->getMetadata()->getFullQualifiedNameClass()
          );
  
          return 'let '.$this->dispatcher->pInfixOp('Expr_AssignRef', $node->var, ' = ', $node->expr);
      }
docs: @param Expr\AssignRef $node
  
  @return string