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);
  }

   * 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