def createCategoryFilter(self, filterName, positiveExamples, negativeExamples=[]):
        """Get a classifier filter (fingerprint) for positive and negative text samples
        Args:
            filterName, str: A unique name for the filter. (required)
            positiveExamples, list(str): The list of positive example texts. (required)
            negativeExamples, list(str): The list of negative example texts. (optional)
        Returns:
            CategoryFilter
        Raises:
            CorticalioException: if the request was not successful
        """
        samples = {"positiveExamples": [{"text": s} for s in positiveExamples],
                   "negativeExamples": [{"text": s} for s in negativeExamples]}
        body = json.dumps(samples)
        return self._classify.createCategoryFilter(self._retina, filterName, body)