code: @Trivial
      public static boolean isSymbol(String s) {
          if (s.length() > 3 && s.charAt(0) == '$' && s.charAt(1) == '{')
              return true;
  
          return false;
      }
docs: Tests if the input string start with the ${ symbolic characters.
  
  @param s The string to test.
  @return True if the input string starts with the ${ symbolic characters. False otherwise.