code: def __call__(self, fn):
      assert self.family not in _log_prob_ratio_registry
      _log_prob_ratio_registry[self.family] = fn
      return fn
  
file_path: probability/tensorflow_probability/python/distributions/log_prob_ratio.py
imports: import inspect
  import tensorflow.compat.v2
  from tensorflow_probability.python.distributions import distribution
label_desc: Use image node_id 2 for calling the RegisterLogProbRatio obj's underlying member method code with example usage: obj.__call__(fn) and returns: fn