getSupportedFunctions());
// add SubtractFunction
generalFunctions.addAll((new SubtractFunctionCluster()).
getSupportedFunctions());
// add MultiplyFunction
generalFunctions.addAll((new MultiplyFunctionCluster()).
getSupportedFunctions());
// add DivideFunction
generalFunctions.addAll((new DivideFunctionCluster()).
getSupportedFunctions());
// add ModFunction