}

  /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
  public static Joiner on(char separator) {
    return new Joiner(String.valueOf(separator));
  }

  private final String separator;

  private Joiner(String separator) {
    this.separator = checkNotNull(separator);
  }

  private Joiner(Joiner prototype) {
    this.separator = prototype.separator;
  }

		for _, join := range joins {
			if _, ok := relationships.Relations[join]; ok && name == join {
				joined = true
				continue
			}
			join0, join1, cut := strings.Cut(join, ".")
			if cut {
				if _, ok := relationships.Relations[join0]; ok && name == join0 {
					joined = true
					nestedJoins = append(nestedJoins, join1)
				}
			}
		}
		return joined, nestedJoins
	}

			builder.WriteString(string(join.Type))
			builder.WriteByte(' ')
		}

		builder.WriteString("JOIN ")
		builder.WriteQuoted(join.Table)

		if len(join.ON.Exprs) > 0 {
			builder.WriteString(" ON ")
			join.ON.Build(builder)
		} else if len(join.Using) > 0 {
			builder.WriteString(" USING (")
			for idx, c := range join.Using {
				if idx > 0 {
					builder.WriteByte(',')
				}
				builder.WriteQuoted(c)

		switch op.Type {
		case clause.OpUnlink, clause.OpDelete:
			joinDB = joinDB.Where("EXISTS (?)", ownersExists)
			if len(op.Conditions) > 0 {
				joinDB = joinDB.Where("EXISTS (?)", relatedExists)
			}
			return joinDB.Delete(nil).Error
		case clause.OpUpdate:
			// Update related table rows that have join rows matching owners

  }

  private static void checkNoOutput(Joiner joiner, Iterable<Integer> set) {
    assertEquals("", joiner.join(set));
    assertEquals("", joiner.join(set.iterator()));

    Object[] array = newArrayList(set).toArray(new Integer[0]);
    assertEquals("", joiner.join(array));

    StringBuilder sb1FromIterable = new StringBuilder();
    assertSame(sb1FromIterable, joiner.appendTo(sb1FromIterable, set));

  }

  private static void checkNoOutput(Joiner joiner, Iterable<Integer> set) {
    assertEquals("", joiner.join(set));
    assertEquals("", joiner.join(set.iterator()));

    Object[] array = newArrayList(set).toArray(new Integer[0]);
    assertEquals("", joiner.join(array));

    StringBuilder sb1FromIterable = new StringBuilder();
    assertSame(sb1FromIterable, joiner.appendTo(sb1FromIterable, set));

  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());

  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected final void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());

  }

  private static final Joiner JOINER = Joiner.on(", ");

  @Override
  protected void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());

      assertEquals(entry.getKey(), bimap.inverse().get(entry.getValue()));
    }

    assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
    assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());
    assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
    assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());