code: def category_fileidset(categorized_corpus, category):
      return set(categorized_corpus.fileids(categories=[category]))
  
file_path: nltk-trainer/nltk_trainer/classification/corpus.py
imports: import itertools
label_desc: Use image node_id 2 for calling a global function with example usage: category_fileidset(categorized_corpus, category) and returns: set