code: def concat(self, n1, n2):
      s = self.new_state()
      m = self.new_state()
      e = self.new_state()
      nfa = NFA(s)
      nfa.insert(s, n1, m)
      nfa.insert(m, n2, e)
      nfa.add_final_state(e)
      return nfa
  
file_path: whoosh/src/whoosh/automata/reg.py
imports: from whoosh.automata.fsa import ANY, EPSILON, NFA
label_desc: Use image node_id 8 for calling the RegexBuilder obj's underlying member method code with example usage: obj.concat(n1, n2) and returns: nfa