Cyclic Quine

A classic Quine is a program which outputs its own source code.
At first, such a program’s existence seems weird if not impossible, as it has to be so self-referential that it knows about itself everything, including how to know about itself. However, writing quines is possible, if not trivial.

A cyclic quine therefore is a program which outputs source code which differs from its own source code, yet outputs the original source code when run (the cycle length could be greater than one). So when running source codes \Psi and \Phi, they output source codes \Phi and \Psi.

Therefore, when one saves the first program as and the second as, one can create both source codes from one another (the following bash commands will not change the files’ contents).

$ python >
$ python >
$ python | python >
$ python | python | python | python | python >

j=0;Q,q="j=1;Q,q={}{}{}.replace(str(j),str(int(not(int(j)))),1),chr(34);print Q.format(q,Q,q)".replace(str(j),str(int(not(int(j)))),1),chr(34);print Q.format(q,Q,q)
j=1;Q,q="j=1;Q,q={}{}{}.replace(str(j),str(int(not(int(j)))),1),chr(34);print Q.format(q,Q,q)".replace(str(j),str(int(not(int(j)))),1),chr(34);print Q.format(q,Q,q)