docs: def truncate(self, cfname):
      """
      Truncate will mark and entire column family as deleted.
      From the user's perspective a successful call to truncate will result complete data deletion from cfname.
      Internally, however, disk space will not be immediatily released, as with all deletes in cassandra, this one
      only marks the data as deleted.
      The operation succeeds only if all hosts in the cluster at available and will throw an UnavailableException if
      some hosts are down.
  
      Parameters:
       - cfname
      """
      self._seqid += 1
      d = self._reqs[self._seqid] = defer.Deferred()
      self.send_truncate(cfname)
      return d