docs: def dataset_filepath(filename, dataset_name=None, task=None, **kwargs):
      """Get the path of the corresponding dataset file.
  
      Parameters
      ----------
      filename : str
          The name of the file.
      dataset_name : str, optional
          The name of the dataset. Used to define a sub-directory to contain all
          instances of the dataset. If not given, a dataset-specific directory is
          not created.
      task : str, optional
          The task for which the dataset in the desired path is used for. If not
          given, a path for the corresponding task-agnostic directory is
          returned.
      **kwargs : extra keyword arguments
          Extra keyword arguments, representing additional attributes of the
          dataset, are used to generate additional sub-folders on the path.
          For example, providing 'lang=en' will results in a path such as
          '/barn_base_dir/regression/lang_en/mydataset.csv'. Hierarchy always
          matches lexicographical order of keyword argument names, so 'lang=en'
          and 'animal=dog' will result in a path such as
          'barn_base_dir/task_name/animal_dof/lang_en/dset.csv'.
  
      Returns
      -------
      str
          The path to the desired dataset file.
      """
      dataset_dir_path = dataset_dirpath(
          dataset_name=dataset_name, task=task, **kwargs)
      return os.path.join(dataset_dir_path, filename)