docs: def accountSummary(self, account: str = '') -> List[AccountValue]:
          """
          List of account values for the given account,
          or of all accounts if account is left blank.
  
          This method is blocking on first run, non-blocking after that.
  
          Args:
              account: If specified, filter for this account name.
          """
          if not self.wrapper.acctSummary:
              # loaded on demand since it takes ca. 250 ms
              self.reqAccountSummary()
          if account:
              return [v for v in self.wrapper.acctSummary.values()
                      if v.account == account]
          else:
              return list(self.wrapper.acctSummary.values())