'Estimate the object size.'

@property
def _size(self):

    try:
        size = object_size(self.info)
    except Exception:
        warn('Could    not    get    size    for    self.info')
        return (-1)
    if hasattr(self, 'data'):
        size += object_size(self.data)
    elif hasattr(self, '_data'):
        size += object_size(self._data)
    return size
