+ #
+ # assert 'l'.search_index_in("hello world", 0) == 2
+ # assert 'l'.search_index_in("hello world", 3) == 3
+ # assert 'z'.search_index_in("hello world", 0) == -1
+ #
+ # This method is usually faster than `search_in` if what is
+ # required is only the index.
+ # Note: in most implementation, `search_in` is implemented with this method.
+ protected fun search_index_in(s: Text, from: Int): Int is abstract