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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 filter(self, exclude):
 """Return a HeaderSet excluding the headers in the exclude list."""

        filtered_headers = HeaderDict()
        lowercased_ignore_list = [x.lower() for x in exclude]

        for header, value in iteritems(self):
            if header.lower() not in lowercased_ignore_list:
                filtered_headers[header] = value

        return filtered_headers