code: function isIdentifierChar(code, astral) {
    if (code < 48) return code === 36;
    if (code < 58) return true;
    if (code < 65) return false;
    if (code < 91) return true;
    if (code < 97) return code === 95;
    if (code < 123) return true;
    return code >= 0xaa;
  }
docs: Test whether a given character is part of an identifier.