code: def conll_demo():
      """
      A demonstration of how to read a string representation of
      a CoNLL format dependency tree.
      """
      dg = DependencyGraph(conll_data1)
      tree = dg.tree()
      tree.pprint()
      print(dg)
      print(dg.to_conll(4))
  
imports: import subprocess
  import warnings
  from collections import defaultdict
  from itertools import chain
  from pprint import pformat
  from nltk.internals import find_binary
  from nltk.tree import Tree
label_desc: Use image node_id 4 for calling a global function with example usage: conll_demo() without return types