docstr: Show a single block on screen
docstr_tok: ["Show","a","single","block","on","screen"]
code: def show(self, index=None):
      """Show a single block on screen"""
  
      index = self._get_index(index)
      if index is None:
          return
  
      print(
          self.marquee(
              "<%s> block # %s (%s remaining)"
              % (self.title, index, self.nblocks - index - 1)
          )
      )
      print(self.src_blocks_colored[index])
      sys.stdout.flush()
  
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 12 for calling the Demo obj's underlying member method code with example usage: obj.show(index) without return types