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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 load_cdx_for_dupe(self, url, timestamp, digest, cdx_loader):
 """ If a cdx_server is available, return response from server, otherwise empty list """

        if not cdx_loader:
            return iter([])

        filters = []

        filters.append('!mime:warc/revisit')

        if digest and digest != '-':
            filters.append('digest:' + digest)

        params = dict(url=url,
                      closest=timestamp,
                      filter=filters)

        return cdx_loader(params)