code: def get_src_blocks(self, seed=None):
          
  
          if seed:
              self.state = seed
  
          blockseed = self.state
          d = self._sample_d()
          have = 0
          nums = set()
          while have < d:
              num = self._get_next() % self.K
              if num not in nums:
                  nums.add(num)
                  have += 1
          return blockseed, d, nums
docs: Returns the indices of a set of `d` source blocks
          sampled from indices i = 1, ..., K-1 uniformly, where
          `d` is sampled from the RSD described above.