Advanced retrieval for AI with Chroma

I am unable to execute the code cell with below part:
[START
token_splitter = SentenceTransformersTokenTextSplitter(chunk_overlap=0, tokens_per_chunk=256)

token_split_texts =
for text in character_split_texts:
token_split_texts += token_splitter.split_text(text)

print(word_wrap(token_split_texts[10]))
print(f"\nTotal chunks: {len(token_split_texts)}")
END]
ERROR: “ImportError: Could not import sentence_transformer python package. This is needed in order to for SentenceTransformersTokenTextSplitter. Please install it with pip install sentence-transformers.”

Note: I tried re-installing and updating sentence_transformer but still it is not working.
Appreciate some help here!
Thanks in advance!
//BR
Pratyush