code: public final Ix<T> takeUntil(IxPredicate<? super T> stopPredicate) {
          return new IxTakeUntil<T>(this, nullCheck(stopPredicate, "stopPredicate is null"));
      }
docs: Take elements from this sequence until the given predicate returns true
  for the current element (checked after emission of that element).
  <p>
  The result's Iterator forwards calls of remove() to this' Iterator.
  @param stopPredicate the function receiving the current element and returns
  true if no further elements should be emitted after this element.
  @return the new Ix instance
  @throws NullPointerException if stopPredicate is null
  @since 1.0