code: def getHighOrderSequenceChunk(it, switchover=1000, w=40, n=2048):
    
    if it%10==3:
      s = numpy.random.randint(5)
      if it <= switchover:
        if s==0:
          label="XABCDE"
        elif s==1:
          label="YCBEAF"
        elif s==2:
          label="GHIJKL"
        elif s==3:
          label="WABCMN"
        else:
          label="ZDBCAE"
      else:
        if s==0:
          label="XCBEAF"
        elif s==1:
          label="YABCDE"
        elif s==2:
          label="GABCMN"
        elif s==3:
          label="WHIJKL"
        else:
          label="ZDHICF"
  
      vecs = letterSequence(label)
    else:
      vecs= [getRandomVector(w, n)]
      label="."
  
    return vecs,label
docs: Given an iteration index, returns a list of vectors to be appended to the
    input stream, as well as a string label identifying the sequence. This
    version generates a bunch of high order sequences. The first element always
    provides sufficient context to predict the rest of the elements.
  
    After switchover iterations, it will generate a different set of sequences.