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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 find_config_files():
 """Return a list of default configuration files. """


    config_files = []

    for config_dir in _get_config_dirs():
        path = os.path.join(config_dir, "rapport.conf")
        if os.path.exists(path):
            config_files.append(path)

    return list(filter(bool, config_files))