code: private static boolean isIdentifierChar(int c)
      {
          return (c >= '0' && c <= '9')
              || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
              || c == '-' || c == '+' || c == '.' || c == '_' || c == '&';
      }
docs: /*
  [0..9a..bA..B-+._&]