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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _add_path(dir_name, payload_info_list):
 """Add a key with the path to each payload_info_dict."""

    for payload_info_dict in payload_info_list:
        file_name = payload_info_dict['filename'] or payload_info_dict['pid']
        payload_info_dict['path'] = d1_common.utils.filesystem.gen_safe_path(
            dir_name, 'data', file_name
        )