/**
   * Returns a string copy of the input character sequence, with each matching BMP character
   * replaced by a given replacement sequence. For example:
   *
   * <pre>{@code
   * CharMatcher.is('a').replaceFrom("yaha", "oo")
   * }</pre>
   *
   * ... returns {@code "yoohoo"}.
   *
   * <p><b>Note:</b> If the replacement is a fixed string with only one character, you are better