code: def metastable_sets(self):
          
          res = []
          assignment = self.metastable_assignment
          for i in range(self.m):
              res.append(np.where(assignment == i)[0])
          return res
docs: Crisp clustering using PCCA. This is only recommended for visualization purposes. You *cannot* compute any
          actual quantity of the coarse-grained kinetics without employing the fuzzy memberships!
          Returns
          -------
          A list of length equal to metastable states. Each element is an array with microstate indexes contained in it