It is something like query.filter.first, but we want to return index of selected element, not value of element.
int indexOf(T value)
int indexOf(Predicate<T> value)
int indexOfEach(EachPredicate<T> value)
Maybe we should return OptionalInt instead of -1?
It is something like `query.filter.first`, but we want to return index of selected element, not value of element.
```
int indexOf(T value)
int indexOf(Predicate<T> value)
int indexOfEach(EachPredicate<T> value)
```
Maybe we should return OptionalInt instead of -1?
It is something like
query.filter.first, but we want to return index of selected element, not value of element.Maybe we should return OptionalInt instead of -1?
not implemented:
int indexOfEach(EachPredicate<T> value)