docstr: Checks that when we set ``true_count`` elements to "truthy", and others to "falsy",
  we get the expected return.
  We check for both True / False, and truthy / falsy values 'a' and '', and verify that
  they can safely be used in any combination.
  NOTSET values should be ignored.
docstr_tok: ["Checks","that","when","we","set","``","true_count","``","elements","to","``","truthy","''",",","and","others","to","``","falsy","''",",","we","get","the","expected","return",".","We","check","for","both","True","\/","False",",","and","truthy","\/","falsy","values","'","a","'","and","``",",","and","verify","that","they","can","safely","be","used","in","any","combination",".","NOTSET","values","should","be","ignored","."]
code: def test_at_most_one(self):
      """
      Checks that when we set ``true_count`` elements to "truthy", and others to "falsy",
      we get the expected return.
      We check for both True / False, and truthy / falsy values 'a' and '', and verify that
      they can safely be used in any combination.
      NOTSET values should be ignored.
      """
  
      def assert_at_most_one(
          true=0, truthy=0, false=0, falsy=0, notset=0
      ):
          sample = []
          for truth_value, num in [
              (True, true),
              (False, false),
              ("a", truthy),
              ("", falsy),
              (NOTSET, notset),
          ]:
              if num:
                  sample.extend([truth_value] * num)
          if sample:
              expected = True if true + truthy in (0, 1) else False
              assert at_most_one(*sample) is expected
  
      for row in itertools.product(range(4), repeat=4):
          print(row)
          assert_at_most_one(*row)
  
imports: from __future__ import annotations
  import itertools
  import re
  from typing import TYPE_CHECKING
  import pytest
  from airflow.exceptions import AirflowException
  from airflow.jobs.base_job_runner import BaseJobRunner
  from airflow.utils import helpers, timezone
  from airflow.utils.helpers import at_most_one, build_airflow_url_with_query, exactly_one, merge_dicts, prune_dict, validate_group_key, validate_key
  from airflow.utils.types import NOTSET
  from tests.test_utils.config import conf_vars
  from tests.test_utils.db import clear_db_dags, clear_db_runs
label_desc: Use image node_id 18 for calling the TestHelpers obj's underlying member method code with example usage: obj.test_at_most_one() without return types