from transformers import T5Tokenizer, AutoModelForCausalLM, T5ForConditionalGeneration

tokenizer = T5Tokenizer.from_pretrained("t5-small", use_fast=False)
model = T5ForConditionalGeneration.from_pretrained("t5-small")


bad_words = ["my", "will", "My", "you", "are", "I", "You", "it"] # words should not be generated 
bad_words_ids = tokenizer(bad_words, add_prefix_space=True, add_special_tokens=False).input_ids # get bad words ids 

input_context = "You are my friend"
# encode input context
input_ids = tokenizer(input_context, return_tensors="pt").input_ids
outputs = model.generate(input_ids=input_ids, max_length=20, do_sample=True, bad_words_ids=bad_words_ids, num_return_sequences=3)
gen_texts = tokenizer.batch_decode(outputs, skip_special_tokens=True)