import tensorflow as tf

    """
    with tf.name_scope('Encode'):
      return self._encode(boxes, anchors)

  def decode(self, rel_codes, anchors):
    """Decode boxes that are encoded relative to an anchor collection.

    Args:
      rel_codes: a tensor representing N relative-encoded boxes
      anchors: BoxList of anchors

    Returns:
      boxlist: BoxList holding N boxes encoded in the ordinary way (i.e.,
        with corners y_min, x_min, y_max, x_max)
    """
    with tf.name_scope('Decode'):
      return self._decode(rel_codes, anchors)

  @abstractmethod
  def _encode(self, boxes, anchors):
    """Method to be overriden by implementations.

    Args:
      boxes: BoxList holding N boxes to be encoded
      anchors: BoxList of N anchors

    Returns:
      a tensor representing N relative-encoded boxes
    """
    pass
