presto-main/src/main/java/io/prestosql/operator/window/LastValueFunction.java/LastValueFunction/LastValueFunction
class LastValueFunction:    public LastValueFunction(List<Integer> argumentChannels, boolean ignoreNulls)
    {
        this.argumentChannel = getOnlyElement(argumentChannels);
        this.ignoreNulls = ignoreNulls;
    }