/**
\example fifthdirection.cpp

Here's a riddle, of a sort.  <i>When embedded in a grid, how many IXMs
can an IXM talk to directly?</i>

The answer, of course, is \e five: Its four neighbors -- to the north,
south, east, and west -- and it can talk to itself as well.

While this is not a great riddle, it does raise a point: Since a
sketch can simply do:

\code
  facePrintf(NORTH,"you are north of me\n");
  facePrintf(SOUTH,"you are south of me\n");
  facePrintf(EAST,"you are east of me\n");
  facePrintf(WEST,"you are west of me\n");
\endcode

to send packets to the four points of the compass, why can't a sketch
send a packet to itself -- or more properly, to its \e future self --
in a similar way?

The answer is that a sketch can do exactly that, using a special
'working memory' face named #WMEM:

\code
  facePrintf(WMEM,"you ARE me (in the future)\n");
\endcode

It is also possible to do this via the #Memory object:

\code
  Memory.printf("you ARE me (in the future)\n");
\endcode

Packets printed to #WMEM aren't sent offboard at all; they are stored
locally in RAM, and reflex-triggered some time in the (usually near)
future, as seen in this tiny sketch, which toggles an LED whenever a
't' packet is received, or when the button is pushed -- using the
talk-to-self power of #WMEM in the latter case.

 */
