Token Calculation Warning for "qwen-plus" Model in Letta Library

[ccxx2017]

When using Letta with the Qwen-plus model, I consistently encounter the following warning:

d:\AI-practicing\Lettagent\env-letta-agent\Lib\site-packages\letta\local_llm\utils.py:215: UserWarning: num_tokens_from_messages() is not implemented for model qwen-plus. See https://github.com/openai/openai-python/blob/main/chatml.md for information on how messages are converted to tokens.
warnings.warn(
Warning: model not found. Using cl100k_base encoding.
Additional Observations:

The warning appears in the local_llm/utils.py file
It suggests that token calculation method is not implemented for the qwen-plus model
The system defaults to using cl100k_base encoding