code: def test_log():
      for array in arrays:
          s = Stream.source(array, dtype="float")
          w = s.log().rename("w")
          expected = list(pd.Series(array).apply(np.log))
  
          assert_op([w], expected)
  
file_path: tensortrade/tests/tensortrade/unit/feed/api/float/test_utils.py
imports: import numpy
  import pandas
  from itertools import product
  from tensortrade.feed import Stream
  from tests.utils.ops import assert_op
label_desc: Use image node_id 5 for calling a global function with example usage: test_log() without return types