code: function char(c) {
    const inState = new NFAState();
    const outState = new NFAState({
      accepting: true,
    });
  
    return new NFA(inState.addTransition(c, outState), outState);
  }
docs: ----------------------------------------------------------------------------- Char NFA fragment: `c` 
  Char factory.
  
  Creates an NFA fragment for a single char.
  
  [in] --c--> [out]