docs: def _lookup_handler(name):
      """
      Look up the implementation of a named handler.  Broken out for
      testing purposes.
  
      :param name: The name of the handler to look up.
  
      :returns: A factory function for the log handler.
      """
  
      # Look up and load the handler factory
      for ep in pkg_resources.iter_entry_points('bark.handler', name):
          try:
              # Load and return the handler factory
              return ep.load()
          except (ImportError, pkg_resources.UnknownExtra):
              # Couldn't load it...
              continue
  
      raise ImportError("Unknown log file handler %r" % name)