T result = uncheckedCastNullableTToT(next);
    next = null;
    return result;
  }

  @Override
  public final void remove() {
    throw new UnsupportedOperationException();
  }

    assertTrue(cycle.hasNext());
    assertEquals("a", cycle.next());
    cycle.remove();
    assertEquals(singletonList("b"), iterable);
    assertTrue(cycle.hasNext());
    assertEquals("b", cycle.next());
    assertTrue(cycle.hasNext());
    assertEquals("b", cycle.next());
    cycle.remove();
    assertEquals(emptyList(), iterable);
    assertFalse(cycle.hasNext());
  }

        final LineIterator it = new LineIterator(reader);
        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is("aaa"));
        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is("bbb"));
        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is("ccc"));
        assertThat(it.hasNext(), is(not(true)));
    }

    /**
     * @throws Exception
     */
    @Test

        this.existPrePage = existPrePage;
    }

    /**
     * Checks if a next page exists.
     * @return true if a next page exists, false otherwise.
     */
    public boolean isExistNextPage() {
        return existNextPage;
    }

    /**
     * Sets whether a next page exists.
     * @param existNextPage true if a next page exists, false otherwise.
     */

    Iterator<Entry<E>> entryIterator = entryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    Iterator<Entry<E>> entryIterator = descendingEntryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  public @Nullable Entry<E> pollFirstEntry() {

        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is(sameInstance(cl3)));

        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is(sameInstance(cl2)));

        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is(sameInstance(cl1)));

        assertThat(it.hasNext(), is(not(true)));
    }

          return this;
        case CLOSED:
          C next = domain.next(endpoint);
          return (next == null) ? Cut.belowAll() : belowValue(next);
      }
      throw new AssertionError();
    }

    @Override
    Cut<C> withUpperBoundType(BoundType boundType, DiscreteDomain<C> domain) {
      switch (boundType) {
        case OPEN:
          C next = domain.next(endpoint);

    }

    /**
     * Checks if a next page exists.
     *
     * @return true if next page exists, false otherwise
     */
    public boolean isExistNextPage() {
        return existNextPage;
    }

    /**
     * Sets whether a next page exists.
     *
     * @param existNextPage true if next page exists, false otherwise
     */

    assertEquals((Integer) 12, it.next());
    assertEquals((Integer) 30, it.next());
    assertEquals((Integer) 40, it.next());
    // Skipping 20
    assertEquals((Integer) 11, it.next());
    // Not skipping 400, because it moved back down
    assertEquals((Integer) 400, it.next());
    assertEquals((Integer) 13, it.next());
    assertEquals((Integer) 200, it.next());
    assertEquals((Integer) 300, it.next());

    final Runnable runnable;
    final Executor executor;
    @Nullable RunnableExecutorPair next;

    RunnableExecutorPair(
        Runnable runnable, Executor executor, @Nullable RunnableExecutorPair next) {
      this.runnable = runnable;
      this.executor = executor;
      this.next = next;
    }
  }