code: def n_chunks(self, chunksize, stride=1, skip=0):
          
          if chunksize != 0:
              chunksize = float(chunksize)
              chunks = int(sum((ceil(l / chunksize) for l in self.trajectory_lengths(stride=stride, skip=skip))))
          else:
              chunks = self.number_of_trajectories(stride)
          return chunks
docs: how many chunks an iterator of this sourcde will output, starting (eg. after calling reset())
  
          Parameters
          ----------
          chunksize
          stride
          skip