code: def hall_demo():
      npp = ProbabilisticNonprojectiveParser()
      npp.train([], DemoScorer())
      for parse_graph in npp.parse(
          ["v1", "v2", "v3"], [None, None, None]
      ):
          print(parse_graph)
  
imports: import logging
  import math
  from nltk.parse.dependencygraph import DependencyGraph
label_desc: Use image node_id 2 for calling a global function with example usage: hall_demo() without return types