public <R> Plan0<R> then(Func9<T1, T2, T3, T4, T5, T6, T7, T8, T9, R> selector) {
        if (selector == null) {
            throw new NullPointerException();
        }
        return new Plan9<T1, T2, T3, T4, T5, T6, T7, T8, T9, R>(this, selector);
    }
public < R > Plan0 < R > then ( Func9 < T1 , T2 , T3 , T4 , T5 , T6 , T7 , T8 , T9 , R > selector ) { if ( selector == null ) { throw new NullPointerException ( ) ; } return new Plan9 < T1 , T2 , T3 , T4 , T5 , T6 , T7 , T8 , T9 , R > ( this , selector ) ; }
Matches when all observable sequences have an available
element and projects the elements by invoking the selector function.

@param selector
the function that will be invoked for elements in the source sequences.
@return the plan for the matching
@throws NullPointerException
if selector is null