return 3;
    }

    @Override
    public char charAt(int index) {
      return "foo".charAt(index);
    }

    @Override
    public CharSequence subSequence(int start, int end) {
      return "foo".subSequence(start, end);
    }

    @Override
    public String toString() {
      throw new AssertionFailedError("shouldn't be invoked");
    }
  }

  // Don't do this.

    int p = 0;
    while (p < maxPrefixLength && a.charAt(p) == b.charAt(p)) {
      p++;
    }
    if (validSurrogatePairAt(a, p - 1) || validSurrogatePairAt(b, p - 1)) {
      p--;
    }
    return a.subSequence(0, p).toString();
  }

  /**
   * Returns the longest string {@code suffix} such that {@code a.toString().endsWith(suffix) &&

  }

  /**
   * Returns a splitter that considers any subsequence matching {@code pattern} to be a separator.
   * For example, {@code Splitter.on(Pattern.compile("\r?\n")).split(entireFile)} splits a string
   * into lines whether it uses DOS-style or UNIX-style line terminators.
   *
   * @param separatorPattern the pattern that determines whether a subsequence is a separator. This
   *     pattern may not match the empty string.

  }

  /**
   * Returns a splitter that considers any subsequence matching {@code pattern} to be a separator.
   * For example, {@code Splitter.on(Pattern.compile("\r?\n")).split(entireFile)} splits a string
   * into lines whether it uses DOS-style or UNIX-style line terminators.
   *
   * @param separatorPattern the pattern that determines whether a subsequence is a separator. This
   *     pattern may not match the empty string.

      return 3;
    }

    @Override
    public char charAt(int index) {
      return "foo".charAt(index);
    }

    @Override
    public CharSequence subSequence(int start, int end) {
      return "foo".subSequence(start, end);
    }

    @Override
    public String toString() {
      throw new AssertionFailedError("shouldn't be invoked");
    }
  }

  // Don't do this.

   * some cases it may alter the input. For example, if the factory returns a sliced view of a
   * source created with some given bytes, this method would return a subsequence of the given
   * (byte[]) data.
   */
  T getExpected(T data);

  /** Cleans up anything created when creating the source or sink. */
  public abstract void tearDown() throws IOException;

    for (; idx < encodedLen; idx++) {
      c = encoded.charAt(idx);

      if (c == '&' || c == '?' || c == '!' || c == ':' || c == ',') {
        break;
      }
    }

    stack.push(reverse(encoded.subSequence(start, idx)));

    if (c == '!' || c == '?' || c == ':' || c == ',') {
      // '!' represents an interior node that represents a REGISTRY entry in the map.

    int p = 0;
    while (p < maxPrefixLength && a.charAt(p) == b.charAt(p)) {
      p++;
    }
    if (validSurrogatePairAt(a, p - 1) || validSurrogatePairAt(b, p - 1)) {
      p--;
    }
    return a.subSequence(0, p).toString();
  }

  /**
   * Returns the longest string {@code suffix} such that {@code a.toString().endsWith(suffix) &&

   * some cases it may alter the input. For example, if the factory returns a sliced view of a
   * source created with some given bytes, this method would return a subsequence of the given
   * (byte[]) data.
   */
  T getExpected(T data);

  /** Cleans up anything created when creating the source or sink. */
  public abstract void tearDown() throws IOException;

        break;
      }
    }
    for (last = len - 1; last > first; last--) {
      if (!matches(sequence.charAt(last))) {
        break;
      }
    }

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

  /**
   * Returns a substring of the input character sequence that omits all matching BMP characters from
   * the beginning of the string. For example:
   *