code: def test_combination(self):
      self.assertIsNotNone(self.utils.combination())
  
      self.assertEqual(self.utils.combination(), 1)
      self.assertEqual(self.utils.combination(r=-1), 1)
  
      self.assertEqual(
          self.utils.combination(n=10, r=4, repetition=False), 210
      )
      self.assertEqual(
          self.utils.combination(n=10, r=4, repetition=True), 715
      )
  
imports: from .config import sample_data
  from .context import pandas_ta
  from unittest import skip, TestCase
  from unittest.mock import patch
  import numpy
  import numpy.testing
  from pandas import DataFrame, Series
  from pandas.api.types import is_datetime64_ns_dtype, is_datetime64tz_dtype
label_desc: Use image node_id 11 for calling the TestUtilities obj's underlying member method code with example usage: obj.test_combination() without return types