The two subroutines are encode/decode routines.  The different names cause
the program to encode/decode, instead of printing "The Perl Journal".


Try "echo hello world |perl sink", and "echo _._ |perl swim".


A simple character gets encoded to 3 characters on each of 2 lines.


The statement  ``(?n?&&open O,"|-")?y|-| ||print O K:print o'' would be
clearer if it was split into separate statements.  This statement is the
key to the structure of the program.