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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def apply_trend_constraint(self, limit, dt, **kwargs):
 """ 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. """

        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