code: func (w *wallet) Contains(account accounts.Account) bool {
  	w.stateLock.RLock()
  	defer w.stateLock.RUnlock()
  
  	_, exists := w.paths[account.Address]
  	return exists
  }
docs: // Contains implements accounts.Wallet, returning whether a particular account is
  // or is not pinned into this wallet instance. Although we could attempt to resolve
  // unpinned accounts, that would be an non-negligible hardware operation.