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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 add_config_paths(**kwargs):
 """ Add to the pool of available configuration files for BIDSLayout. Args: kwargs: dictionary specifying where to find additional config files. Keys are names, values are paths to the corresponding .json file. Example: > add_config_paths(my_config='/path/to/config') > layout = BIDSLayout('/path/to/bids', config=['bids', 'my_config']) """


    for k, path in kwargs.items():
        if not os.path.exists(path):
            raise ValueError(
                'Configuration file "{}" does not exist'.format(k))
        if k in cf.get_option('config_paths'):
            raise ValueError('Configuration {!r} already exists'.format(k))

    kwargs.update(**cf.get_option('config_paths'))
    cf.set_option('config_paths', kwargs)