code: def get_monotone_constraints(self):
          
          if self.monotone_constraints is None:
              self.monotone_constraints = self.get_field('monotone_constraints')
          return self.monotone_constraints
docs: Get the monotone constraints of the Dataset.
  
          Returns
          -------
          monotone_constraints : numpy array or None
              Monotone constraints: -1, 0 or 1, for each feature in the Dataset.