code: def regret_met(self, threshold=None):
          '''
          Determine if regret criterion has been met.
  
          Parameters
          ----------
          threshold : float
  
          Returns
          -------
          bool
          '''
  
          if not threshold:
              return self.regret() <= self.stop_value
          elif self.regret() <= threshold:
              return True
          else:
              return Falsf regret_met(self, threshold=None):
          '''
          Determine if regret criterion has been met.
  
          Parameters
          ----------
          threshold : float
  
          Returns
          -------
          bool
          '''
  
          if not threshold:
              return self.regret() <= self.stop_value
          elif self.regret() <= threshold:
              return True
          else:
              return False
docs: Determine if regret criterion has been met.
  
          Parameters
          ----------
          threshold : float
  
          Returns
          -------
          bool