new_contents: from bart.common import Utils
  import unittest
  import pandas as pd
  
  
  class TestCommonUtils(unittest.TestCase):
  
      def __init__(self, *args, **kwargs):
          super(TestCommonUtils, self).__init__(*args, **kwargs)
  
      def test_interval_sum(self):
          """Test Utils Function: interval_sum"""
  
          array = [0, 0, 1, 1, 1, 1, 0, 0]
          series = pd.Series(array)
          self.assertEqual(Utils.interval_sum(series, 1), 3)
  
          array = [False, False, True, True, True, True, False, False]
          series = pd.Series(array)
          self.assertEqual(Utils.interval_sum(series), 3)
  
          array = [0, 0, 1, 0, 0, 0]
          series = pd.Series(array)
          self.assertEqual(Utils.interval_sum(series, 1), 0)
  
          array = [0, 0, 1, 0, 1, 1]
          series = pd.Series(array)
          self.assertEqual(Utils.interval_sum(series, 1), 1)
  
subject: Add test case for interval_sum