code: def __call__(self, fn):
      assert self.cls not in _fldj_ratio_registry
      _fldj_ratio_registry[self.cls] = fn
      return fn
  
file_path: probability/tensorflow_probability/python/bijectors/ldj_ratio.py
imports: import inspect
  import tensorflow.compat.v2
  from tensorflow_probability.python.bijectors import bijector
  from tensorflow_probability.python.internal import prefer_static
label_desc: Use image node_id 2 for calling the RegisterFLDJRatio obj's underlying member method code with example usage: obj.__call__(fn) and returns: fn