code: def complain(distribution_name):
      
      try:
          pkg_resources.get_distribution(distribution_name)
          warnings.warn(
              "The {pkg} distribution is now obsolete. "
              "Please `pip uninstall {pkg}`. "
              "In the future, this warning will become an ImportError.".format(
                  pkg=distribution_name
              ),
              DeprecationWarning,
          )
      except pkg_resources.DistributionNotFound:
          pass
docs: Issue a warning if `distribution_name` is installed.
  
      In a future release, this method will be updated to raise ImportError
      rather than just send a warning.
  
      Args:
          distribution_name (str): The name of the obsolete distribution.