volume.py

#! /usr/bin/env python

import sys
import time

import pychromecast

requested_volume = float(sys.argv[1]) if len(sys.argv) > 1 else None

cast = pychromecast.get_chromecast(friendly_name="Roo's Chromecast")

time.sleep(0.5)

if requested_volume != None:
    cast.set_volume(requested_volume)
else:
    print cast.status.volume_level