from transformers import AutoTokenizer
tokenizer = AutoTokenizer.from_pretrained("NousResearch/Llama-2-7b-chat-hf")

chat = [
   {"role": "system", "content": "lorem"},
   {"role": "user", "content": "abc"},
   {"role": "assistant", "content": "ipsum"},
   {"role": "user", "content": "123"},
   {"role": "assistant", "content": "sit"},
]

ids = tokenizer.apply_chat_template(chat)
print(tokenizer.decode(ids))