return false, Boolean, nil
		}
		return nil, Unknown, d.mkError(ErrSyntax, "in literal false")
	case 't':
		if d.remaining() < 3 {
			return nil, Unknown, d.mkError(ErrUnexpectedEOF)
		}
		//nolint:gocritic
		if d.next() == 'r' && d.next() == 'u' && d.next() == 'e' {
			return true, Boolean, nil
		}
		return nil, Unknown, d.mkError(ErrSyntax, "in literal true")
	case 'n':
		if d.remaining() < 3 {

        initialReferral.append(appendedReferral);

        // Then
        assertEquals(appendedReferral, initialReferral.next,
                "The 'next' property of the initial referral should point to the appended referral.");
        assertEquals(initialReferral, appendedReferral.next,
                "The 'next' property of the appended referral should point back to the initial referral, closing the loop.");
    }

    /**

        itr.next();
        itr.next();
        itr.next();
    }

    /**
     *
     */
    @Test
    public void testHasNext() {
        final ArrayIterator<String> itr = new ArrayIterator<String>("A", "B");
        assertThat(itr.hasNext(), is(true));
        itr.next();
        assertThat(itr.hasNext(), is(true));
        itr.next();
        assertThat(itr.hasNext(), is(not(true)));

     */
    @Override
    public boolean hasNext() {
        return this.next != null;
    }

    /**
     * {@inheritDoc}
     *
     * @see java.util.Iterator#next()
     */
    @Override
    public SmbResource next() {
        final SmbResource n = this.next;
        this.next = advance();
        return n;
    }

    /**
     * {@inheritDoc}
     *

        // hasNext/next sequence over two elements
        assertTrue(it.hasNext(), "Expected first element available");
        SmbResource r1 = it.next();
        assertNotNull(r1);
        assertEquals("foo/", r1.getName(), "First child name should match with trailing slash");

        assertTrue(it.hasNext(), "Expected second element available");
        SmbResource r2 = it.next();
        assertNotNull(r2);

    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());
  }

      int initialSize = map.size();
      boolean didRemove = entrySet.remove(entrySet.iterator().next());
      assertTrue(didRemove);
      assertEquals(initialSize - 1, map.size());
    } else {
      assertThrows(
          UnsupportedOperationException.class, () -> entrySet.remove(entrySet.iterator().next()));
    }
    assertInvariants(map);
  }

  public void testEntrySetRemoveMissingKey() {

        // Act
        assertTrue(it.hasNext());
        assertEquals("first", it.next().getName()); // initial
        assertTrue(it.hasNext());
        FileEntry next = it.next();

        // Assert: "bad" was skipped due to filter exception, "good" returned
        assertNotNull(next);
        assertEquals("good", next.getName());
        assertFalse(it.hasNext());
        verify(tree, times(1)).release();
    }

The main [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank} should be enough to give you a tour through all the main features of **FastAPI**.

In the next sections you will see other options, configurations, and additional features.

/// tip

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

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

///

        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();