request for the soft key [copy]

[compsystems]

x:=3 [enter] 3 ok
x++ [enter]=> increment(x) => 4 ok // increment operator very useful in programming
x-- [enter] => decrement(x) => 3 ok // decrement operator very useful in programming
++x [enter] => pre-increment(x) => ERROR undefined ok
--x [enter] => pre-decrement(x) => ERROR undefined ok

but

[±] => − (unary negative operator, 2212 Unicode value) ≠ [-] => - (minus, 45 Unicode value). the line has different size

[±] x => −x [enter] -3 ok
[±] (x) [enter] => -(x) => -3 ok

[±] [up] [up] [copy] [enter] => −-X ERROR WHY? IS PARSE BUG?

−-X => negative(-X) => (-*-)X => +X => x the negative of a negative number is positive, signs law