code: def test_abs():
      s = Stream.source([3, -4, 6, -7, 2, -6], dtype="float")
  
      s1 = s.abs().rename("s1")
      s2 = abs(s).rename("s2")
  
      assert_op([s1, s2], [3, 4, 6, 7, 2, 6])
  
file_path: tensortrade/tests/tensortrade/unit/feed/api/float/test_operations.py
imports: import pandas
  from tensortrade.feed import Stream
  from tests.utils.ops import assert_op
label_desc: Use image node_id 9 for calling a global function with example usage: test_abs() without return types