I've only briefly looked through the source, so I'm not sure if they're doing this, but you can sort of intercept operators like `+` by implementing valueOf() o

I've only briefly looked through the source, so I'm not sure if they're doing this, but you can sort of intercept operators like `+` by implementing valueOf() on the object. When you perform a primitive operation on an object, the VM calls valueOf() on it to get a primitive value that it can handle. It does not tell you what operation caused valueOf to be called, nor does it let you influence the result (except by the primitive value you choose to return). I suspect that they're doing something else, and given the Syncify.parallel construct, I don't think they're blocking the whole thread.