code: def build(self):
          
          if self.is_built_coherence() is Build.NO:
              with tf.name_scope(self.tf_name_scope):
                  self._build()
docs: Implementation for ICompilable interface `build` method. Builds tensors within
          TensorFlow name scope using parentable node's name. Hidden name is used when 
          no parent exists for current node.
  
          :raises GPflowError: Node's parts were built with different graph and differ from
              default TensorFlow graph.