class_docstr: Attention layer according to https://arxiv.org/abs/1409.0473.
  
  Params:
    num_units: Number of units used in the attention layer
code: def __init__(self, params, mode, name="attention"):
      GraphModule.__init__(self, name)
      Configurable.__init__(self, params, mode)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import abc
  import six
  import tensorflow
  from tensorflow.python.framework import function
  from seq2seq.graph_module import GraphModule
  from seq2seq.configurable import Configurable
label_desc: Use image node_id 1 to create a new AttentionLayer object from inherited base classes: GraphModule, Configurable with example: obj = AttentionLayer(params, mode, name)