code: def dataset_exists(dataset_name):
      '''If a dataset with the given name exists, return its absolute path; otherwise return None'''
      dataset_dir = os.path.join(LIB_DIR, 'datasets')
      dataset_path = os.path.join(dataset_dir, dataset_name)
      
      return dataset_path if os.path.isdir(dataset_path) else Nonf dataset_exists(dataset_name):
      '''If a dataset with the given name exists, return its absolute path; otherwise return None'''
      dataset_dir = os.path.join(LIB_DIR, 'datasets')
      dataset_path = os.path.join(dataset_dir, dataset_name)
      
      return dataset_path if os.path.isdir(dataset_path) else None
docs: If a dataset with the given name exists, return its absolute path; otherwise return None