code: def is_chunk_start(prev_tag, tag):
      """
      check if a new chunk started between the previous and current word
      """
      prefix1, chunk_type1 = split_tag(prev_tag)
      prefix2, chunk_type2 = split_tag(tag)
  
      if prefix2 == "O":
          return False
      if prefix1 == "O":
          return prefix2 != "O"
  
      if chunk_type1 != chunk_type2:
          return True
  
      return prefix2 in ["B", "S"] or prefix1 in ["E", "S"]
  
file_path: graph4nlp/examples/pytorch/name_entity_recognition/conlleval.py
imports: from __future__ import division, print_function, unicode_literals
  import sys
  from collections import defaultdict
label_desc: Use image node_id 3 for calling a global function with example usage: is_chunk_start(prev_tag, tag) and returns: unknown, False, unknown, True