code: def test_empty_string():
      nfa = fsa.NFA(1)
      nfa.add_final_state(1)
  
      assert nfa.accept("")
      assert not nfa.accept("a")
  
      dfa = nfa.to_dfa()
      assert dfa.accept("")
      assert not dfa.accept("a")
  
imports: import gzip
  import os.path
  from bisect import bisect_left
  from whoosh.compat import permutations
  from whoosh.compat import xrange
  from whoosh.automata import fsa, glob, lev
  from whoosh.support.levenshtein import levenshtein
label_desc: Use image node_id 2 for calling a global function with example usage: test_empty_string() without return types