code: def test_decaying(self):
      self.start_tests(name="decaying")
  
      exploration = dict(
          type="decaying",
          decay="exponential",
          unit="timesteps",
          num_steps=5,
          initial_value=0.1,
          decay_rate=0.5,
      )
      self.float_unittest(exploration=exploration)
  
      horizon = dict(
          type="polynomial",
          unit="timesteps",
          num_steps=1,
          initial_value=2,
          final_value=4,
          power=2,
      )
      self.int_unittest(horizon=horizon)
  
file_path: tensorforce/test/test_parameters.py
imports: import unittest
  from test.unittest_base import UnittestBase
label_desc: Use image node_id 4 for calling the TestParameters obj's underlying member method code with example usage: obj.test_decaying() without return types