Method append_null

datafusion/spark/src/function/string/substring.rs:307–309

(&mut self)

        GenericStringBuilder::append_value(self, val);
    }
    fn append_null(&mut self) {
        GenericStringBuilder::append_null(self);
    }
    fn append_empty(&mut self) {
        GenericStringBuilder::append_value(self, "");
    }