Python string error, can you help me please?

[Andrix951]

i created an AI chatbot with python but the compiler gives me an error, post the error code, string 12:

import random
import json
import pickle
import numpy as np

import nltk
from nltk.stem import WordNetLemmatizer

from tensorflow.keras.models import load_model

lemmatizer = WordNetLemmatizer()
intents = json.loads(open('intents.json').read())

words = pickle.load(open('word.pkl', 'rb'))
classes = pickle.load(open('classes.pkl', 'rb'))
model = load_model('chatbot_model.model')

def clean_up_sentence(sentence):
sentence_words = nltk.word_tokenize(sentence)
sentence_words = [lemmatizer.lemmatize(word) for word in sentence_words]
return sentence_words

def bag_of_words(sentence):
sentence_words = clean_up_sentence(sentence)
bag = [o] * len(words)
for w in sentence_words:
for i, word in enumerate(words):
if word == w:
bag[i] = 1
return np.array(bag)

def predict_class(sentence):
bow = bag_of_words(sentence)
res = model.predict(np.array([bow]))[0]
ERROR_TRASHOLD = 0.25
results = [[i, r] for i, r in enumerate(red) if r > ERROR_TRASHOLD]

results.key(key=lambda x: x[1], reverse=True)
return_list = []
for r in results:
return_list.append({'intent': classes[r[0]], 'probability': str(r[1])})
return return_list