def METHOD_NAME(*col_lists):
    """
    Transforms the column names to lowercase.
    e.g.
    lowercase(col_list = [('A', ...), ('B', ...), ('C', ...)], [...])
    returns [[('a', ...), ('b', ...), ('c', ...)], [...]]
    """
    return [
        [(col[0].lower(), *col[1:]) for col in col_list]
        for col_list in col_lists
    ]