code: def halflife_decay(
      time_step,
      half_life,
      initial,
      final=0.0,
      dtype=tf.float32,
      name=None,
  ):
      """Interpolates `initial` to `final` using halflife (exponential) decay."""
      with tf.name_scope(name or "halflife_decay"):
          dtype = dtype_util.common_dtype(
              [initial, final, half_life], dtype_hint=tf.float32
          )
          initial = tf.convert_to_tensor(
              initial, dtype=dtype, name="initial"
          )
          final = tf.convert_to_tensor(final, dtype=dtype, name="final")
          half_life = tf.convert_to_tensor(
              half_life, dtype=dtype, name="half_life"
          )
          time_step = tf.cast(time_step, dtype=dtype, name="time_step")
          return final + (initial - final) * 0.5 ** (
              time_step / half_life
          )
  
imports: import collections
  import contextlib
  import functools
  import sys
  import numpy
  import tensorflow.compat.v2
  from tensorflow_probability.python.internal import dtype_util
  from tensorflow_probability.python.internal import prefer_static
  from tensorflow_probability.python.internal import tensorshape_util
label_desc: Use image node_id 13 for calling a global function with example usage: halflife_decay(time_step, half_life, initial, final, dtype, name) and returns: unknown