dart_double_the_words

import 'dart:io';
import 'package:okay/okay.dart';
void main(List <String> args){
  if (args.length!=2){
    print("please provide valid inputs!");
    return;
  }
  final input = File(args[1]);
  if (!input.existsSync()){
    print("please create the input file!");
  }
  try{
    String inputcontent = input.readAsStringSync();
    String modifiedcontent = modify(inputcontent);
    input.writeAsStringSync(modifiedcontent);
  } catch(e){
    print("oops!");
  }
  return ;
}

String modify(String s){
  final lines = s.split('\n');
  List<String> keywords = [];
  for (String line in lines){
    List words = line.split(' ');
    for (String word in words){
      keywords.add(word);
      keywords.add(word);
    }
  }
  final m = keywords.join('\n');
  return m;
}