Maybe an operator-overloading region?

    #{
       m3 = m1 * m2 + m3;
       m3 += m4;
    }

Basically, pure syntactic sugar to help the author express intent without having to add a bunch of line-chatter.

Speaking of operator-overloading, I really wish C++ (anyone!) had a `.` prefix for operator-overloading which basically says "this is more arguments for the highest-precedence operator in the current expression:

    a := b * c .+ d;

Which translates to:

    a := fma(b, c, d)