code: def test_optimal_leverage(self):
      result = pandas_ta.optimal_leverage(self.close)
      self.assertIsInstance(result, int)
      result = pandas_ta.optimal_leverage(self.close, log=True)
      self.assertIsInstance(result, int)
  
imports: from unittest import skip, TestCase
  from pandas import DataFrame
  from .config import sample_data
  from .context import pandas_ta
label_desc: Use image node_id 12 for calling the TestUtilityMetrics obj's underlying member method code with example usage: obj.test_optimal_leverage() without return types