code: def load_writer(writer, ppp_config_dir=None, **writer_kwargs):
      
      if ppp_config_dir is None:
          ppp_config_dir = get_environ_config_dir()
  
      config_fn = writer + ".yaml" if "." not in writer else writer
      config_files = config_search_paths(
          os.path.join("writers", config_fn), ppp_config_dir)
      writer_kwargs.setdefault("config_files", config_files)
      if not writer_kwargs['config_files']:
          raise ValueError("Unknown writer '{}'".format(writer))
  
      try:
          return load_writer_configs(writer_kwargs['config_files'],
                                     ppp_config_dir=ppp_config_dir,
                                     **writer_kwargs)
      except ValueError:
          raise ValueError("Writer '{}' does not exist or could not be "
                           "loaded".format(writer))
docs: Find and load writer `writer` in the available configuration files.