text: import 'dart:io';
  
  String READ(String x) => x;
  
  String EVAL(String x) => x;
  
  String PRINT(String x) => x;
  
  String rep(String x) => PRINT(EVAL(READ(x)));
  
  const prompt = 'user> ';
  main() {
    while (true) {
      stdout.write(prompt);
      var input = stdin.readLineSync();
      if (input == null) return;
      var output = rep(input);
      stdout.writeln(output);
    }
  }
  