code: def _create_variables(self, n_features):
          
          w_name = 'weights'
          self.W = tf.Variable(tf.truncated_normal(
              shape=[n_features, self.num_hidden], stddev=0.1), name=w_name)
          tf.summary.histogram(w_name, self.W)
  
          bh_name = 'hidden-bias'
          self.bh_ = tf.Variable(tf.constant(0.1, shape=[self.num_hidden]),
                                 name=bh_name)
          tf.summary.histogram(bh_name, self.bh_)
  
          bv_name = 'visible-bias'
          self.bv_ = tf.Variable(tf.constant(0.1, shape=[n_features]),
                                 name=bv_name)
          tf.summary.histogram(bv_name, self.bv_)
docs: Create the TensorFlow variables for the model.
  
          :param n_features: number of features
          :return: self