text: var fs=require('fs')
  var dirpath=process.argv[2]
  var ext=process.argv[3]
  
  function doneReading(err,list){
      if (err) throw err
      list=list.filter(function chosen (filepath){
  	name=filepath.split('.')[0]
  	extension=filepath.split('.')[1]
  	return extension == ext
      }
  
  		    )
  
      for(var i=0;i<list.length;i++){
  	console.log(list[i]);
      }
  }
  fs.readdir(dirpath,doneReading)
  