Compute a value for the given event. Return undefined
if we don't find a mapped value.
Return DoNotSetAnyGoals (null) to shortcut evaluation of the present set of rules,
terminating evaluation and guarantee the return of undefined if we've reached this point.
Only do so if you are sure
that this evaluation must be short circuited if it has reached this point.
If a previous rule has matched, it will still be used.
The value may be static
or computed on demand, depending on the implementation.
Compute a value for the given event. Return undefined if we don't find a mapped value. Return DoNotSetAnyGoals (null) to shortcut evaluation of the present set of rules, terminating evaluation and guarantee the return of undefined if we've reached this point. Only do so if you are sure that this evaluation must be short circuited if it has reached this point. If a previous rule has matched, it will still be used. The value may be static or computed on demand, depending on the implementation.