code: def check(branch: str = 'master'):
      
      if os.environ.get('TRAVIS') == 'true':
          travis(branch)
      elif os.environ.get('SEMAPHORE') == 'true':
          semaphore(branch)
      elif os.environ.get('FRIGG') == 'true':
          frigg(branch)
      elif os.environ.get('CIRCLECI') == 'true':
          circle(branch)
      elif os.environ.get('GITLAB_CI') == 'true':
          gitlab(branch)
      elif 'BITBUCKET_BUILD_NUMBER' in os.environ:
          bitbucket(branch)
docs: Detects the current CI environment, if any, and performs necessary
      environment checks.
  
      :param branch: The branch that should be the current branch.