class_docstr: The module is the OpenRec abstraction for modules. A module may belong to one of the three categories,     **extractions**, **fusions**, and **interactions**, depending on its functionality (Read [1]_ for details).
  
  Parameters
  ----------
  train: bool, optional
      An indicator for training or servining phase.
  l2_reg: float, optional
      Weight for L2 regularization, i.e., weight decay.
  scope: str, optional
      Scope for module variables.
  reuse: bool, optional
      Whether or not to reuse module variables.
  
  Notes
  -----
  The module abstraction is used to construct recommenders. It should be extended by all module implementations.     During initialization, functions :code:`self._build_shared_graph`, :code:`self._build_training_graph`, and     :code:`self._build_serving_graph` are called as follows.
  
  .. image:: module.png
      :scale: 50 %
      :alt: The structure of the module abstraction
      :align: center
  
  A module implementation should follow two steps below:
  
  * **Build computational graphs.** Override :code:`self._build_shared_graph()`, :code:`self._build_training_graph()`,     and/or :code:`self._build_serving_graph()` functions to build training/serving computational graphs.
  
  * **Define a loss and an output list.** Define a loss (:code:`self._loss`) to be included in training and an output     list of Tensorflow tensors (:code:`self._outputs`).
  
  References
  ----------
  .. [1] Yang, L., Bagdasaryan, E., Gruenstein, J., Hsieh, C., and Estrin, D., 2018, June. 
      OpenRec: A Modular Framework for Extensible and Adaptable Recommendation Algorithms.
      In Proceedings of WSDM'18, February 5-9, 2018, Marina Del Rey, CA, USA.
docstr: Build training-specific computational graphs (may be overridden).
          
docstr_tok: ["Build","training-specific","computational","graphs","(","may","be","overridden",")","."]
code: def _build_training_graph(self):
      """Build training-specific computational graphs (may be overridden)."""
      pass
  
file_path: openrec/openrec/tf1/legacy/modules/module.py
imports: import tensorflow
label_desc: Use image node_id 3 for calling the Module obj's underlying member method code with example usage: obj._build_training_graph() without return types