code: def get_layer_timing_signal_sinusoid_1d(channels, layer, num_layers):
    
  
    signal = get_timing_signal_1d(num_layers, channels)
    layer_signal = tf.expand_dims(signal[:, layer, :], axis=1)
  
    return layer_signal
docs: Add sinusoids of different frequencies as layer (vertical) timing signal.
  
    Args:
      channels: dimension of the timing signal
      layer: layer num
      num_layers: total number of layers
  
    Returns:
      a Tensor of timing signals [1, 1, channels].