code: def get_default(key):
      metric, args, kwargs = __defaults__[key]
      if inspect.isclass(metric):
          metric = metric(*args, **kwargs)
      return metric
  
imports: import inspect
  from torchbearer import Metric, no_grad
label_desc: Use image node_id 2 for calling a global function with example usage: get_default(key) and returns: metric