code: @Override
  	protected void xFunc() throws SQLException {
  
  		int argCount = args();
  		if (argCount != 1) {
  			throw new SQLException("Single argument is required. args: "
  					+ argCount);
  		}
  
  		byte[] bytes = value_blob(0);
  		GeoPackageGeometryData geometryData = null;
  		if (bytes != null && bytes.length > 0) {
  			geometryData = new GeoPackageGeometryData(bytes);
  		}
  
  		Object response = execute(geometryData);
  
  		if (response == null) {
  			result();
  		} else if (response instanceof Double) {
  			result((Double) response);
  		} else if (response instanceof Boolean) {
  			result(Boolean.compare((Boolean) response, false));
  		} else {
  			throw new SQLException("Unexpected response value: " + response
  					+ ", of type: " + response.getClass().getSimpleName());
  		}
  
  	}
docs: {@inheritDoc}