code: def register_onnx_layer_handler(layer_name, handler_func):
      if layer_name in layer_handlers:
          raise Exception(f"Layer {layer_name} already registered")
      else:
          layer_handlers[layer_name] = handler_func
  
imports: import numpy
  import onnx
  from onnx import helper, numpy_helper, shape_inference
  from hls4ml.model import ModelGraph
label_desc: Use image node_id 7 for calling a global function with example usage: register_onnx_layer_handler(layer_name, handler_func) without return types