code: def get_header_field_list(main_fields, entity_type, entity_fields):
      if _is_composed_key(entity_type):
          key, value = _get_key_value_composed(entity_type)
          main_entity = key
          sub_entity = value
      else:
          main_entity = None
          sub_entity = entity_type
  
      if main_entity:
          output1 = [
              HIER_SEPARATOR.join([main_entity, x]) for x in main_fields
          ]
      else:
          output1 = main_fields
      output2 = [
          HIER_SEPARATOR.join([sub_entity, x]) for x in entity_fields
      ]
      return output1 + output2
  
file_path: nltk/nltk/twitter/common.py
imports: import csv
  import gzip
  import json
  from nltk.internals import deprecated
label_desc: Use image node_id 10 for calling a global function with example usage: get_header_field_list(main_fields, entity_type, entity_fields) and returns: unknown