php equivalent of python lxlm.etree fromstring

I'm fairly new to python and I'm re-writing a python script that accesses an API.

In the python script, I'm trying to find the equivalient of this:

response = get_resource(url, auth=(username,password), params=params)
return lxml.etree.fromstring(response.content)

returns <http://ift.tt/r5ut6F} feed at 0x2f12b70>

What is the equivalent of this code in php? And I'm not even sure what this is returning?

Thanks.