class_docstr: Composition of multiple `_RankingHead.
  
  The main functionality is to create an estimator spec that
    - merges all predictions from all heads.
    - merges all eval metrics from all heads.
    - combines all the losses using weights from all heads.
class_docstr_tok: ["Composition","of","multiple","`","_RankingHead",".","The","main","functionality","is","to","create","an","estimator","spec","that","-","merges","all","predictions","from","all","heads",".","-","merges","all","eval","metrics","from","all","heads",".","-","combines","all","the","losses","using","weights","from","all","heads","."]
docstr: See `_AbstractRankingHead`.
docstr_tok: ["See","`","_AbstractRankingHead","`","."]
code: def name(self):
      """See `_AbstractRankingHead`."""
      return "_".join([h.name for h in self._heads])
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import abc
  import six
  import tensorflow
  from tensorflow import estimator
label_desc: Use image node_id 2 for calling the _MultiRankingHead obj's underlying member method code with example usage: obj.name() and returns: str