Brainfork
From Esolang
Brainfork is a multithreaded variant of Brainfuck, invented by Asger Ipsen in 2004. Brainfork retains Brainfuck's eight commands and adds a ninth, Y, for forking.
When a Y is encountered, the current thread forks, with the current cell being zeroed in the parent thread, and the pointer being moved one to the right and that cell set to 1 in the child.
Because Brainfork is a proper superset of Brainfuck, all Brainfuck programs are also valid Brainfork programs with identical semantics.
Because Brainfuck ignores all unknown instructions (such as Y), all Brainfork programs are also valid Brainfuck programs, although they may (of course) behave very differently.
[edit] Computational class
Brainfork is Turing-complete through a trivial isomorphism with Brainfuck, which is known to be Turing-complete.
