code: def testRandomWalk(self):
      num_values = 10000
      values = np.cumsum(np.random.randn(num_values)) + 1000
      hds = build_hurst(values, num_values - 10, 2, 20)
      self.assertEquals(round(hds[-1], 1), 0.5)
      self.assertEquals(round(hds[-2], 1), 0.5)
  
file_path: pyalgotrade/testcases/technical_hurst_test.py
imports: import numpy
  from .None import common
  from pyalgotrade.technical import hurst
  from pyalgotrade import dataseries
label_desc: Use image node_id 4 for calling the TestCase obj's underlying member method code with example usage: obj.testRandomWalk() without return types