code: function firstStrongCharDir(str: string): BidiDirection {
    const strongChar = firstStrongChar(str);
    if (strongChar == null) {
      return UnicodeBidiDirection.NEUTRAL;
    }
    return REGEX_RTL.exec(strongChar)
      ? UnicodeBidiDirection.RTL
      : UnicodeBidiDirection.LTR;
  }
docs: Returns the direction of a block of text, based on the direction of its
  first strong character (has Bidi_Class value of L, R, or AL).
  
  @param str  A text block; e.g. paragraph, table cell, tag
  @return     The resolved direction