text: #!/usr/bin/env node --harmony --use-strict --harmony_destructuring --harmony_default_parameters
  
  require('./helper')
  let fs = require('fs').promise
  
  function* cat() {
      try {
      if (process.argv.length > 2) {
          let fileContent = yield fs.readFile(process.argv[2]);
          process.stdout.write(fileContent + '\n')
       }
      } catch(error) {
          process.stdout.write(error + '\n')
      }
  }
  module.exports = cat
  