code: func (am *Manager) Find(account Account) (Wallet, error) {
  	am.lock.RLock()
  	defer am.lock.RUnlock()
  
  	for _, wallet := range am.wallets {
  		if wallet.Contains(account) {
  			return wallet, nil
  		}
  	}
  	return nil, ErrUnknownAccount
  }
docs: // Find attempts to locate the wallet corresponding to a specific account. Since
  // accounts can be dynamically added to and removed from wallets, this method has
  // a linear runtime in the number of wallets.