assertThat(is('x').negate().collapseFrom(inout, '_')).isSameInstanceAs(inout);
    assertThat(anyOf("-").collapseFrom(inout, '_')).isSameInstanceAs(inout);
    assertThat(anyOf("-#").collapseFrom(inout, '_')).isSameInstanceAs(inout);
    assertThat(anyOf("-#123").collapseFrom(inout, '_')).isSameInstanceAs(inout);
    assertThat(CharMatcher.none().collapseFrom(inout, '_')).isSameInstanceAs(inout);
  }

      result += matcher.countIn(teststring);
    }
    return result;
  }

  @Benchmark
  public int collapseFrom(int reps) {
    int result = 0;
    CharMatcher matcher = this.matcher;
    String teststring = this.teststring;
    for (int i = 0; i < reps; i++) {
      result += System.identityHashCode(matcher.collapseFrom(teststring, ' '));
    }
    return result;
  }

  private static String allMatchingChars(BitSet bitSet) {

      result += matcher.countIn(teststring);
    }
    return result;
  }

  @Benchmark
  public int collapseFrom(int reps) {
    int result = 0;
    CharMatcher matcher = this.matcher;
    String teststring = this.teststring;
    for (int i = 0; i < reps; i++) {
      result += System.identityHashCode(matcher.collapseFrom(teststring, ' '));
    }
    return result;
  }

  private static String allMatchingChars(BitSet bitSet) {

   * BMP characters replaced by a single replacement character. For example:
   *
   * {@snippet :
   * CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-')
   * }
   *
   * ... returns {@code "b-p-r"}.
   *
   * <p>The default implementation uses {@link #indexIn(CharSequence)} to find the first matching

   * BMP characters replaced by a single replacement character. For example:
   *
   * {@snippet :
   * CharMatcher.anyOf("eko").collapseFrom("bookkeeper", '-')
   * }
   *
   * ... returns {@code "b-p-r"}.
   *
   * <p>The default implementation uses {@link #indexIn(CharSequence)} to find the first matching