FETCH
            This method will be triggered every time the tied
            variable is accessed (read).  It takes no arguments
            beyond its self reference, which is the object
            representing the scalar we're dealing with.  Because
            in this case we're using just a SCALAR ref for the
            tied scalar object, a simple $$self allows the method
            to get at the real value stored there.  In our
            example below, that real value is the process ID to
            which we've tied our variable.