docs: def prune_chunks(self, tsn):
          """
          Prune chunks up to the given TSN.
          """
          pos = -1
          size = 0
          for i, chunk in enumerate(self.reassembly):
              if uint32_gte(tsn, chunk.tsn):
                  pos = i
                  size += len(chunk.user_data)
              else:
                  break
  
          self.reassembly = self.reassembly[pos + 1:]
          return size