code: def entropy_variance(data, class_attr=None,
      method=DEFAULT_CONTINUOUS_METRIC):
      
      assert method in CONTINUOUS_METRICS, "Unknown entropy variance metric: %s" % (method,)
      assert (class_attr is None and isinstance(data, dict)) \
          or (class_attr is not None and isinstance(data, list))
      if isinstance(data, dict):
          lst = data
      else:
          lst = [record.get(class_attr) for record in data]
      return get_variance(lst)
docs: Calculates the variance fo a continuous class attribute, to be used as an
      entropy metric.