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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 _get_config_files():
 """ Load the list of file paths for fedmsg configuration files. Returns: list: List of files containing fedmsg configuration. """

    config_paths = []
    if os.environ.get('FEDMSG_CONFIG'):
        config_location = os.environ['FEDMSG_CONFIG']
    else:
        config_location = '/etc/fedmsg.d'

    if os.path.isfile(config_location):
        config_paths.append(config_location)
    elif os.path.isdir(config_location):
        # list dir and add valid files
        possible_config_files = [os.path.join(config_location, p)
                                 for p in os.listdir(config_location) if p.endswith('.py')]
        for p in possible_config_files:
            if os.path.isfile(p):
                config_paths.append(p)
    if not config_paths:
        _log.info('No configuration files found in %s', config_location)
    return config_paths