code: def sparse_reindex(self, new_index):
          
          if not isinstance(new_index, splib.SparseIndex):
              raise TypeError("new index must be a SparseIndex")
          values = self.values
          values = values.sp_index.to_int_index().reindex(
              values.sp_values.astype('float64'), values.fill_value, new_index)
          values = SparseArray(values,
                               sparse_index=new_index,
                               fill_value=self.values.fill_value)
          return self._constructor(values, index=self.index).__finalize__(self)
docs: Conform sparse values to new SparseIndex
  
          Parameters
          ----------
          new_index : {BlockIndex, IntIndex}
  
          Returns
          -------
          reindexed : SparseSeries