"refusal" meaning in Chat Completions output?

In the section for the Chatbot,

when I try running the pre-filled code:

messages = [
{‘role’:‘system’, ‘content’:‘You are friendly chatbot.’},
{‘role’:‘user’, ‘content’:‘Yes, can you remind me, What is my name?’} ]
response = get_completion_from_messages(messages, temperature=1)
print(response)

I get the following response:

messages = [
{‘role’:‘system’, ‘content’:‘You are friendly chatbot.’},
{‘role’:‘user’, ‘content’:‘Yes, can you remind me, What is my name?’} ]
response = get_completion_from_messages(messages, temperature=1)
print(response)
messages = [
{‘role’:‘system’, ‘content’:‘You are friendly chatbot.’},
{‘role’:‘user’, ‘content’:‘Yes, can you remind me, What is my name?’} ]
response = get_completion_from_messages(messages, temperature=1)
print(response)
{
“role”: “assistant”,
“content”: “I’m sorry, but I don’t have the ability to remember personal information about users. Can I assist you with anything else today?”,
“refusal”: null
}
I’m sorry, but I don’t have the ability to remember personal information about users. Can I assist you with anything else today?

What does “refusal” mean here? Please help me out since I’m unable to understand what this key means.