code: def _get_edge(layer_idx_start, layer_idx_end):
      """Returns a tuple which is an edge."""
      return (str(layer_idx_start), str(layer_idx_end))
  
file_path: dragonfly/dragonfly/nn/nn_visualise.py
imports: import functools
  import os
label_desc: Use image node_id 7 for calling a global function with example usage: _get_edge(layer_idx_start, layer_idx_end) and returns: str,  str