presto-ml/src/main/java/io/prestosql/plugin/ml/LibSvmUtils.java/LibSvmUtils/parseKernelType
class LibSvmUtils:    private static int parseKernelType(String value)
    {
        switch (value.toLowerCase(ENGLISH)) {
            case "linear":
                return svm_parameter.LINEAR;
            case "poly":
                return svm_parameter.POLY;
            case "rbf":
                return svm_parameter.RBF;
            case "sigmoid":
                return svm_parameter.SIGMOID;
            default:
                throw new PrestoException(INVALID_FUNCTION_ARGUMENT, format("Unknown kernel type %s", value));
        }
    }