code: def _get_num_layers_signal(num_layers, bias_val, decay):
      """A signal based on the number of layers."""
      return np.exp(-decay * abs(num_layers - bias_val))
  
file_path: dragonfly/dragonfly/nn/syn_nn_functions.py
imports: import numpy
label_desc: Use image node_id 6 for calling a global function with example usage: _get_num_layers_signal(num_layers, bias_val, decay) and returns: np