/**
   * Returns a string copy of the input character sequence, with each matching BMP character
   * replaced by a given replacement character. For example:
   *
   * {@snippet :
   * CharMatcher.is('a').replaceFrom("radar", 'o')
   * }
   *
   * ... returns {@code "rodor"}.
   *
   * <p>The default implementation uses {@link #indexIn(CharSequence)} to find the first matching