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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 gateway_client_js():
 """ Template tag which provides a `script` tag for each javascript item required by the payment gateway """

    javascripts = GATEWAY.client_js()
    if isinstance(javascripts, (tuple, list)):
        tags = []
        for js in javascripts:
            tags.append('<script type="text/javascript" src="{}"></script>'.format(js))
        return tags
    else:
        raise TypeError(
            'function client_js of {} must return a list or tuple'.format(GATEWAY.__name__))