assertEquals(
        "next() should still return first element after peeking", "A", peekingIterator.next());

    assertEquals("Should be able to peek() at middle element", "B", peekingIterator.peek());
    assertEquals(
        "Should be able to peek() middle element multiple times", "B", peekingIterator.peek());
    assertEquals(

    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());

    assertEquals(o1, three.next().target);
    assertFalse(three.hasNext());

    three = registry.getSubscribers("");

    registry.unregister(s2);

    assertEquals(s1, three.next().target);
    assertEquals(s2, three.next().target);
    assertEquals(o1, three.next().target);
    assertFalse(three.hasNext());

    Iterator<Subscriber> two = registry.getSubscribers("");
    assertEquals(s1, two.next().target);

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

        buf.append(cause.getMessage()).append(" : [");
        SQLException next = cause.getNextException();
        while (next != null) {
            buf.append(MessageFormatter.getSimpleMessage("ECL0071", next.getMessage(), Integer.toString(next.getErrorCode()),
                    next.getSQLState())).append("], [");
            next = next.getNextException();
        }
        Throwable t = cause.getCause();

	s.pos++
	if s.pos >= len(s.tokens) {
		return scanner.EOF
	}
	return s.tokens[s.pos].ScanToken
}

func (s *Slice) Text() string {
	return s.tokens[s.pos].text
}

func (s *Slice) File() string {
	return s.base.Filename()
}

func (s *Slice) Base() *src.PosBase {
	return s.base
}

func (s *Slice) SetBase(base *src.PosBase) {

        assertThat(i.next(), is("bbb"));
        assertThat(i.next(), is("ccc"));
        assertThat(i.next(), is("aaa"));
        lru.put("ddd", "444");
        assertThat(lru.size(), is(3));
        assertThat(lru.get("bbb"), is(nullValue()));
        i = lru.keySet().iterator();
        assertThat(i.next(), is("ccc"));
        assertThat(i.next(), is("aaa"));
        assertThat(i.next(), is("ddd"));

    int hash = Hashing.smearedHash(key);
    int tableIndex = hash & mask;
    int next = tableGet(table, tableIndex);
    if (next == UNSET) {
      return -1;
    }
    int hashPrefix = getHashPrefix(hash, mask);
    int lastEntryIndex = -1;
    do {
      int entryIndex = next - 1;
      int entry = entries[entryIndex];
      if (getHashPrefix(entry, mask) == hashPrefix

            }
          }
        };

    assertTrue(iter.hasNext());
    assertEquals(0, (int) iter.next());

    // verify idempotence of hasNext()
    assertTrue(iter.hasNext());
    assertTrue(iter.hasNext());
    assertTrue(iter.hasNext());
    assertEquals(1, (int) iter.next());

    assertFalse(iter.hasNext());

    // Make sure computeNext() doesn't get invoked again

            }
          }
        };

    assertTrue(iter.hasNext());
    assertEquals(0, (int) iter.next());

    // verify idempotence of hasNext()
    assertTrue(iter.hasNext());
    assertTrue(iter.hasNext());
    assertTrue(iter.hasNext());
    assertEquals(1, (int) iter.next());

    assertFalse(iter.hasNext());

    // Make sure computeNext() doesn't get invoked again