docstr: Move the seek pointer back num blocks (default is 1).
docstr_tok: ["Move","the","seek","pointer","back","num","blocks","(","default","is","1",")","."]
code: def back(self, num=1):
      """Move the seek pointer back num blocks (default is 1)."""
      self.seek(self.block_index - num)
  
imports: import os
  import re
  import shlex
  import sys
  import pygments
  from pathlib import Path
  from IPython.utils.text import marquee
  from IPython.utils import openpy
  from IPython.utils import py3compat
label_desc: Use image node_id 8 for calling the Demo obj's underlying member method code with example usage: obj.back(num) without return types