[Feature Request] Sum up previous lines

Is your feature request related to a problem? Please describe. Summing up a couple of numbers is what I mostly need a calculator for, and I suspect I'm not alone. The Mac apps Soulver, Numi and also the Numerals plugin have a "magic variable" that sums up all the above lines. (Up to an empty line or another kind of separator like a ## Headline.) But I can't do this very easily in Solve. (At least I don't know how?)

Describe the solution you'd like A syntax something like this. (Just as an example: two lines declare variables, one doesn't, one has a calculation.)

Apples = 10 Oranges = 20 10 1 + 1 @sum = 42

(Github makes links out of "@", that's not the intention :-)

Describe alternatives you've considered Could also be something else than "@sum" or "@total", if those seem like they would conflict with something. (":sum" or ":total" ?)