====== NFA Python Implementation ======

Consider the following encoding of an NFA:
<code>
   <number_of_states>
   <list_of_chars_in_alphabet>
   <list_of_final_states>
   <state> <symbol> <list_of_states>
</code>

Example:
<code>
9
a b
4
0 EPS 1
0 a 5
0 b 0
1 EPS 2
1 b 3 5
2 EPS 4
2 a 2 3
3 a 3
3 b 3
4 EPS 4 7 8
5 a 6
5 b 5
6 EPS 7
6 a 6
7 EPS 6
7 b 4
</code>

You'll find in //nfa_skel.rar// a class that already reads the input and forms the NFA.

Also, you can use the **graphvizNFA** method to get a graphical representation of the NFA, but you will have to install the //graphviz// library.
<code>
   pip install graphviz
</code>

Implement (in Python) an NFA class that supports the following methods:

1. **step(configuration)**
  * returns a list with all reachable configurations in //one step//.
  * an epsilon transition is also considered a step. 

2. **kstep(configuration, k)**
  * returns a list including all reachable configurations in //k steps//
  * an epsilon transition is also considered a step.
  * the final list contains only the states where we stopped, not the entire path to them.
  * if no transitions are available and $ k > 0 $, return an empty list

3. **accept(self, word: Word)**
  * True or False if the NFA accepts the given word.

4. **epsilonClosure(self, state: State)**
  * the set of all states where we can go from the current state by going through epsilon transitions

5. **emptyLanguage(self)**
  * True or False if the NFA's accepted language is the Empty Language

{{:lfa:nfa_skel.rar|}}