docs: def update(self, goal: Dict=None) -> None:
          """Update a single savings goals data."""
          if goal is None:
              endpoint = "/account/{0}/savings-goals/{1}".format(
                  self._account_uid,
                  self.uid
              )
  
              response = get(
                  _url(endpoint, self._sandbox),
                  headers=self._auth_headers
              )
              response.raise_for_status()
              goal = response.json()
  
          self.uid = goal.get('savingsGoalUid')
          self.name = goal.get('name')
  
          target = goal.get('target', {})
          self.target_currency = target.get('currency')
          self.target_minor_units = target.get('minorUnits')
  
          total_saved = goal.get('totalSaved', {})
          self.total_saved_currency = total_saved.get('currency')
          self.total_saved_minor_units = total_saved.get('minorUnits')