Get a HandwrittenData object that has ``raw_data_id`` from a pickle file
       ``path_to_data``.
       :returns: The HandwrittenData object if ``raw_data_id`` is in
                 path_to_data, otherwise ``None``.

def _get_data_from_rawfile(path_to_data, raw_data_id):
    """Get a HandwrittenData object that has ``raw_data_id`` from a pickle file
       ``path_to_data``.
       :returns: The HandwrittenData object if ``raw_data_id`` is in
                 path_to_data, otherwise ``None``."""
    loaded = pickle.load(open(path_to_data, "rb"))
    raw_datasets = loaded['handwriting_datasets']
    for raw_dataset in raw_datasets:
        if raw_dataset['handwriting'].raw_data_id == raw_data_id:
            return raw_dataset['handwriting']
    return None