code: function verifyChecksum(fileName, checksum) {
    return kew.resolve(hasha.fromFile(fileName, {algorithm: 'sha256'})).then(function (hash) {
      var result = checksum == hash
      if (result) {
        console.log('Verified checksum of previously downloaded file')
      } else {
        console.log('Checksum did not match')
      }
      return result
    }).fail(function (err) {
      console.error('Failed to verify checksum: ', err)
      return false
    })
  }
docs: Check to make sure that the file matches the checksum.
  @param {string} fileName
  @param {string} checksum
  @return {Promise.<boolean>}