computeNext

Computes the next item in the iterator.

This callback method should call one of these two methods:

• setNext with the next value of the iteration

• done to indicate there are no more elements

Failure to call either method will result in the iteration terminating with a failed state

Computes the next item in the iterator.

This callback method should call one of these two methods:

• setNext with the next value of the iteration

• done to indicate there are no more elements

Failure to call either method will result in the iteration terminating with a failed state