How can I use #$save partly?

Thank you for giving me a nice extension
but I have a question about how to apply #$save in part of whole codes
like below:
```python
import Calculate
result1 = Calculate.diff(something)
result2 = Calculate.add(something)

# I want to start save from here

def largest_prime_factor(n):
i = 2
while i * i <= n:
if n % i:
i += 1
else:
n //= i
return n

def another_heavy_function(n):
some_heavy_processing
return heavy_res

result_big = largest_prime_factor(8008514751439999)
result_big2 = another_heavy(13123213123)

# I want to stop save from here

other_excute_after_save = Calculate.sum(something)
other_excute_after_save = Calculate.partial(something)
print("code end line")
```
I am so sorry if you have already guided it in your doc.
but I can't find.
I can only see the case that stores from the start of codes to the #$save line