Failed to load vasprun.xml file

Hello dear,

I have some trouble when I parse a DOS object with vasprun.xml obtained from GW calculation.

from import Vasprun
vasprun = Vasprun('vasprun_GW.xml')

The error is as follows:
“NotImplementedError: This vasprun.xml has >2 unlabelled dielectric functions”

How to solve this problem? I also want to parse DOS by using DOSCAR file instead of the vasprun.xml. But I have not found a class that can do this in pymatgen. How can I solve this?