code: def test_exp_biases(temporal_graph):
      rw = TemporalRandomWalk(temporal_graph)
      times = np.array([1, 2, 3])
      t_0 = 1
      expected = np.exp(t_0 - times) / sum(np.exp(t_0 - times))
      biases = rw._exp_biases(times, t_0, decay=True)
      np.testing.assert_allclose(biases, expected)
  
file_path: stellargraph/tests/data/test_temporal_random_walker.py
imports: import pandas
  import pytest
  import numpy
  import networkx
  from stellargraph.data.explorer import TemporalRandomWalk
  from stellargraph.core.graph import StellarGraph
label_desc: Use image node_id 4 for calling a global function with example usage: test_exp_biases(temporal_graph) without return types