Impact
======

If you select the single-agent version of Soar (the default) then
there is no change to any of your existing I/O code.

On the other hand, if you select the multi-agent version of Soar then
any reference to a global will have to be replaced by the use of a
macro to add a layer of abstraction between the I/O system and the
implementation of agent globals.  Hence, a line such as:

mystring = lexeme.string;

will have to be replaced with

mystring = current_agent(lexeme).string;