public void registerFunction(FunctionEntity entity) {
        synchronized (functionMap) {
            if (functionMap.containsKey(entity.getLowerName()))
                exception("Function '%s' already registered", entity.getName());

            functionMap.put(entity.getLowerName(), entity);
        }
    }
Remove all method which does not destruct

@throws Throwable
jphp-runtime/src/php/runtime/env/Environment.java