OR condition in XPath for Scrapy

Currently, I am stuck with the problem in XPath and Scrapy where I have to parse example like this.

<dl class>
<x class="another"><a>data 1</a></x>
<y class="y"><b>data 2</b></y>
</dl>

I want to fetch the data between and tag. So, I was wondering if there is solution like

dl=response.xpath(".//dl")
for row in dl.xpath(".//a or .//b")

I want to know if I can put the OR condition.