code: func (am *Manager) Wallet(url string) (Wallet, error) {
  	am.lock.RLock()
  	defer am.lock.RUnlock()
  
  	parsed, err := parseURL(url)
  	if err != nil {
  		return nil, err
  	}
  	for _, wallet := range am.Wallets() {
  		if wallet.URL() == parsed {
  			return wallet, nil
  		}
  	}
  	return nil, ErrUnknownWallet
  }
docs: // Wallet retrieves the wallet associated with a particular URL.