def default_filter(files):
    """Function to filter folders based on content

    Parameters
    ----------
    files : list
        A list containing strings of filenames in directory

    Returns
    -------
        bool : a flag indicating whether the list contains '1.mkv', '2.mkv'
               and 'Labels.json'
    """

    if '1.mkv' in files and '2.mkv' in files and 'Labels.json' in files:
        return True

    return False