code: public static boolean isTerminal(ArrayList<Configuration> beam)
      {
          for (Configuration configuration : beam)
              if (!configuration.state.isTerminalState())
                  return false;
          return true;
      }
docs: Shows true if all of the configurations in the beam are in the terminal state
  
  @param beam the current beam
  @return true if all of the configurations in the beam are in the terminal state