return sequence.subSequence(0, last + 1).toString();
      }
    }
    return "";
  }

  /**
   * Returns a string copy of the input character sequence, with each group of consecutive matching
   * BMP characters replaced by a single replacement character. For example:
   *
   * {@snippet :
   * CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-')
   * }
   *

          int headIndex = head.getHash() & newMask;

          // Single node on list
          if (next == null) {
            newTable.set(headIndex, head);
          } else {
            // Reuse the consecutive sequence of nodes with the same target
            // index from the end of the list. tail points to the first
            // entry in the reusable list.
            E tail = head;
            int tailIndex = headIndex;

		{"a☺b☻c☹d\xe2\x98�\xff�\xed\xa0\x80", utf8.MaxRune + 1, -1},

		// Test the cutover to bytealg.Index when it is triggered in
		// the middle of rune that contains consecutive runs of equal bytes.
		{"aaaaaKKKK\U000bc104", '\U000bc104', 17}, // cutover: (n + 16) / 8
		{"aaaaaKKKK鄄", '鄄', 17},
		{"aaKKKKKa\U000bc104", '\U000bc104', 18}, // cutover: 4 + n>>4
		{"aaKKKKKa鄄", '鄄', 18},
	}