saw

const co = require('co')
const fs = require('mz/fs')
const path = require('path')

function fixStuff (dir, fullpath = __dirname) {
  return co(function *() {
    const files = yield fs.readdir(path.resolve(fullpath, dir))

    yield files.map(f => {
      if (yield fs.stat(f).isDirectory()) {
        return fixStuff(f, fullpath)
      }
      else {
        if (/\.csv$/.test(f)) {
          yield fs.rename(f, f.replace(/\.csv$/, '.txt'))
        }
      }
    })
  })
}