How to fix an invalid syntax with a set and nodes?

I have an issue with my code. When I try to run it, I have an error: SyntaxError: invalid syntax and it's about this line:

node_names = {-1:'A', -2:'B', 0:'A XOR B'}

What could I fix? I think the syntax is correct. We use curly braces {} to create set? Or maybe must I use set()?

from __future__ import print_function
import os
import neat
import visualize

xor_inputs = [(0.0, 0.0), (0.0, 1.0), (1.0, 0.0), (1.0, 1.0)]
xor_outputs = [(0.0,), (1.0), (1.0), (0.0)]

def eval_genomes(genomes, config):
    for genomes_id, genome in genome:
        genome.fitness = 4.0
        net = neat.nn.FeedForwardNetwork.create(genome, config)
        for xi, xo in zip(xor_inputs, xor_outputs):
            output = net.activate(xi)
            genome.fitness -= (output[0] - xo[0]) ** 2


def run(config_file):
    config = neat.Config(neat.DefaultGenome, neat.DefaultReproduction, neat.DefaultSpeciesSet, neat.DefaultStagnation, config_file)

    p = neat.Population(config)

    p.add_reporter(neat.StdOutReporter(True))
    stats = neat.StatisticsReporter()
    p.add_reporter(stats)
    p.add_reporter(neat.Checkpointer(5))

    winner = p.run(eval_genomes, 300)

    print('\nBest genome:\n{!s}'.format(winner))

    print('\nOutput:')
    winner_net = neat.nn.FeedForwardNetwork.create(winner, config)

    for xi, xo in zip(xor_inputs, xor_outputs):
        output = winner_net.activate(xi)
        print("input {!r}, expected output {!r}, got {!r}".format(xi, xo, output)

    node_names = {-1:'A', -2:'B', 0:'A XOR B'} 

    visualize.draw_net(config, winner, True, node_names=node_names)
    visualize.plot_stats(stats, ylog=False, view=True)
    visualize.plot_species(stats, view=True)

    p = neat.Checkpointer.restore_checkpoint('neat-checkpoint-4')
    p.run(eval_genomes, 10)


if __name__ == '__main__':

    local_dir = os.path.dirname(__file__)
    config_path = os.path.join(local_dir, 'NeatConfigXOR.txt')
    run(config_path)

You forgot closing bracket in this line:

print("input {!r}, expected output {!r}, got {!r}".format(xi, xo, output)

You closed format() but not print(