code: def apply_trend_constraint(self, limit, dt, **kwargs):
          
          if 'RV monitoring' not in self.constraints:
              self.constraints.append('RV monitoring')
          for pop in self.poplist:
              if not hasattr(pop,'dRV'):
                  continue
              pop.apply_trend_constraint(limit, dt, **kwargs)
          self.trend_limit = limit
          self.trend_dt = dt
docs: Applies constraint corresponding to RV trend non-detection to each population
  
          See :func:`stars.StarPopulation.apply_trend_constraint`;
          all arguments passed to that function for each population.