CHAR is the character for which you want to create a new directive
(Quick Start used
#\` as an example). Note that FoCus
allows you to modify standard directives as well as creating new
ones. This means that you can create a completely new directive, freely
override a standard directive with a new meaning, alias a standard
directive to a new character, anything you want.
If such a directive is already set in TABLE, FoCus throws a
table-directive-collision error, unless you explicitely pass a
nil value to the
:force keyword argument.