code: def _activation_summary(x):
    
    # Remove 'tower_[0-9]/' from the name in case this is a multi-GPU training
    # session. This helps the clarity of presentation on tensorboard.
    tf.histogram_summary(x.name + '/activations', x)
    tf.scalar_summary(x.name + '/sparsity', tf.nn.zero_fraction(x))
docs: Helper to create summaries for activations.
    Creates a summary that provides a histogram of activations.
    Creates a summary that measure the sparsity of activations.
    Args:
      x: Tensor
    Returns:
      nothing