code: def test_exponential_decay():
      values = np.array([1, 2, 3, 4, 5, 6])
      expected = np.array([0.25, 0.35355339, 0.5, 0.70710678, 1.0, 1.0])
      actual = exponential_decay(value=values, max_val=5, half_life=2)
      assert np.allclose(actual, expected, atol=TOL)
  
file_path: recommenders/tests/unit/recommenders/utils/test_python_utils.py
imports: import pytest
  import numpy
  from recommenders.utils.python_utils import exponential_decay, jaccard, lift, get_top_k_scored_items, binarize, rescale
label_desc: Use image node_id 7 for calling a global function with example usage: test_exponential_decay() without return types