About assistant example code bug

there is a bug in example code:

# Use the create and poll SDK helper to create a run and poll the status of
# the run until it's in a terminal state.

run = client.beta.threads.runs.create_and_poll(
    thread_id=thread.id, assistant_id=assistant.id
)

messages = list(client.beta.threads.messages.list(thread_id=thread.id, run_id=run.id))

message_content = messages[0].content[0].text
annotations = message_content.annotations
citations = []
for index, annotation in enumerate(annotations):
    message_content.value = message_content.value.replace(annotation.text, f"[{index}]")
    if file_citation := getattr(annotation, "file_citation", None):
        cited_file = client.files.retrieve(file_citation.file_id)
        citations.append(f"[{index}] {cited_file.filename}")

print(message_content.value)
print("\n".join(citations))

message_content = messages[0].content[0].text
after that,message_content is a dict, so the next code:
annotations = message_content.annotations
should be message_content[‘annotations’]