new_contents: from unittest.case import TestCase
  
  from zsl.utils.string_helper import camelcase_to_underscore, underscore_to_camelcase
  
  
  class InflectionTestCase(TestCase):
      def testCamelCaseToUnderscore(self):
          self.assertEquals(
              "camel_case_to_underscore",
              camelcase_to_underscore("camelCaseToUnderscore"),
              "CC to usc conversion"
          )
          self.assertEquals(
              "camel_case_to_underscore",
              camelcase_to_underscore("CamelCaseToUnderscore"),
              "CC to usc conversion"
          )
  
      def testUnderscoreToCamelCase(self):
          self.assertEquals(
              "camelCaseToUnderscore",
              underscore_to_camelcase("camel_case_to_underscore", False),
              "CC to usc conversion"
          )
          self.assertEquals(
              "CamelCaseToUnderscore",
              underscore_to_camelcase("camel_case_to_underscore"),
              "CC to usc conversion"
          )
          self.assertEquals(
              "CamelCaseToUnderscore",
              underscore_to_camelcase("camel_case_to_underscore", True),
              "CC to usc conversion"
          )
subject: Add tests of the improved camelcase/underscore conversion