def get_dummy_stratas(metadatas: dict) -> dict:
    """
    Create a dummy, one-factor 'no_stratification' categorical
    metadata variables to stratify on for each metadata table.

    Parameters
    ----------
    metadatas : dict
        Key     = Metadata file path.
        Value   = Metadata table.

    Returns
    -------
    stratas : dict
        Key     = Metadata file path.
        Value   = List of one dummy 'no_stratification' variable to stratify on.
    """
    stratas = {}
    for md_fp, md in metadatas.items():
        md['no_stratification'] = 'no_stratification'
        stratas[md_fp] = ['no_stratification']
    return stratas