code: def test_lookback():
      assert abstract.Function("SMA", 10).lookback == 9
  
      stochrsi = abstract.Function("stochrsi", 20, 5, 3)
      assert stochrsi.lookback == 26
  
imports: import copy
  import re
  import threading
  import time
  import numpy
  import pytest
  from numpy.testing import assert_array_equal, assert_raises
  import talib
  from talib import abstract, func
label_desc: Use image node_id 12 for calling a global function with example usage: test_lookback() without return types