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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_stream_xcorr(name_or_func=None, concurrency=None):
 """ Return a function for performing normalized cross correlation on lists of streams. :param name_or_func: Either a name of a registered function or a callable that implements the standard array_normxcorr signature. :param concurrency: Optional concurrency strategy, options are below. :return: A callable with the interface of stream_normxcorr :Concurrency options: - multithread - use a threadpool for concurrency; - multiprocess - use a process pool for concurrency; - concurrent - use a customized concurrency strategy for the function, if not defined threading will be used. """

    func = _get_registerd_func(name_or_func)

    concur = concurrency or 'stream_xcorr'
    if not hasattr(func, concur):
        msg = '%s does not support concurrency %s' % (func.__name__, concur)
        raise ValueError(msg)
    return getattr(func, concur)