code: func (ac *accountCache) delete(removed accounts.Account) {
  	ac.mu.Lock()
  	defer ac.mu.Unlock()
  
  	ac.all = removeAccount(ac.all, removed)
  	if ba := removeAccount(ac.byAddr[removed.Address], removed); len(ba) == 0 {
  		delete(ac.byAddr, removed.Address)
  	} else {
  		ac.byAddr[removed.Address] = ba
  	}
  }
docs: // note: removed needs to be unique here (i.e. both File and Address must be set).