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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 nnz_obs_groups(self):
 """ get the observation groups that contain at least one non-zero weighted observation Returns ------- nnz_obs_groups : list a list of observation groups that contain at least one non-zero weighted observation """

        og = []
        obs = self.observation_data
        for g in self.obs_groups:
            if obs.loc[obs.obgnme==g,"weight"].sum() > 0.0:
                og.append(g)
        return og