code: def get_account_from_hash(self, account_hash):
          
          for _, pool in self.pools:
              account = pool.get_account_from_hash(account_hash)
              if account is not None:
                  return account
          return self.default_pool.get_account_from_hash(account_hash)
docs: Returns the account with the given hash, if it is contained in any
          of the pools. Returns None otherwise.
  
          :type  account_hash: str
          :param account_hash: The hash of an account object.