some bugs about mbart50 for spanish
```
from transformers import MBartForConditionalGeneration, MBart50TokenizerFast

model = MBartForConditionalGeneration.from_pretrained("facebook/mbart-large-50-many-to-many-mmt")
tokenizer = MBart50TokenizerFast.from_pretrained("facebook/mbart-large-50-many-to-many-mmt")

article_en = "Hello World"
encoded_en = tokenizer(article_en, return_tensors="pt", padding='longest', truncation=True, max_length=1024)
generated_tokens = model.generate(**encoded_en, forced_bos_token_id=tokenizer.lang_code_to_id["es_XX"])
#tokenizer.batch_decode(generated_tokens, skip_special_tokens=True)
text_es = tokenizer.batch_decode(generated_tokens, skip_special_tokens=True, clean_up_tokenization_spaces=True)
```
text_es
['El Presidente (habla en inglés): Doy las gracias al representante de la República Islámica del Irán por su declaración.']

Looks like this model definitely has some bugs for spanish since this is an easy translation task. the correct answer is "Hola Mundo"
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