code: func (ch Challenge) checkConsistency() error {
  	if ch.Status != StatusPending {
  		return fmt.Errorf("The challenge is not pending.")
  	}
  
  	// There always needs to be a token
  	if !LooksLikeAToken(ch.Token) {
  		return fmt.Errorf("The token is missing.")
  	}
  	return nil
  }
docs: // checkConsistency checks the sanity of a challenge object before issued to the client.