class_docstr: Accumulator for gathering the latest timesteps into sequences.
  
  Note sequences can overlap and cross episode boundaries.
class_docstr_tok: ["Accumulator","for","gathering","the","latest","timesteps","into","sequences",".","Note","sequences","can","overlap","and","cross","episode","boundaries","."]
code: def __init__(self, length):
      self._timesteps = collections.deque(maxlen=length)
  
imports: import collections
  from absl import app
  from absl import flags
  from bsuite.environments import catch
  import dm_env
  import haiku
  from haiku import nets
  import jax
  import jax.numpy
  import numpy
  import optax
  import rlax
  from rlax.examples import experiment
label_desc: Use image node_id 1 to create a new SequenceAccumulator object  with example: obj = SequenceAccumulator(length)