text: 
  import unittest
  import uuid
  from envtools import override_environment, get_bool
  
  
  class TestGetBool(unittest.TestCase):
      def test_get_true_default_strings(self):
          true_strings = [
              "True",
              "true",
              "TRUE",
              "1"
          ]
          for true_string in true_strings:
              with override_environment(BOOL_VAR=true_string):
                  self.assertTrue(get_bool('BOOL_VAR'))
  
      def test_get_true_strings_from_arg(self):
          true_strings = [
              "FOO",
              "BAR",
              "Baz"
          ]
          for true_string in true_strings:
              with override_environment(BOOL_VAR=true_string):
                  self.assertTrue(get_bool('BOOL_VAR', true_strings=true_strings))
  
      def test_get_false(self):
          false_strings = [False, 'false', "None", 0]
          for false_string in false_strings:
              with override_environment(BOOL_VAR=false_string):
                  self.assertFalse(get_bool('BOOL_VAR'))
  
      def test_get_false_on_non_existent(self):
          bool_var = str(uuid.uuid4()).replace('-', '_')
          self.assertFalse(get_bool(bool_var))
  
      def test_get_true_on_non_existent(self):
          bool_var = str(uuid.uuid4()).replace('-', '_')
          self.assertTrue(get_bool(bool_var, True))
  