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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 responses_of(self, request):
 """ Find the responses corresponding to a request. This function isn't actually used by VCR internally, but is provided as an external API. """

        responses = [response for index, response in self._responses(request)]

        if responses:
            return responses
        # The cassette doesn't contain the request asked for.
        raise UnhandledHTTPRequestError(
            "The cassette (%r) doesn't contain the request (%r) asked for"
            % (self._path, request)
        )