The invoke method is to take a particular action. The details of how the method performs the action is implementation specific. ...

The invoke method is to take a particular action. The  details of how the method performs the action is implementation  specific.  The results of the method are based on the return value.    - A 0 (zero) is returned if the condition is satisfied.   - A 1 (one) is returned if the method is not supported.    - Any other value indicates the condition is not satisfied.