docs: def _freemem(conn):
      '''
      Internal variant of freemem taking a libvirt connection as parameter
      '''
      mem = conn.getInfo()[1]
      # Take off just enough to sustain the hypervisor
      mem -= 256
      for dom in _get_domain(conn, iterable=True):
          if dom.ID() > 0:
              mem -= dom.info()[2] / 1024
      return mem