Slack Bot Python - convert the keyword into lowercase

Question

I'm really new to Python. I have been creating a custom bot that replies users in thread. If a user uses a specific keyword bot will answer. But most of the time users will screw up and type uppercase instead of lowercase version of the word. How do I add a line where it converts the message into lowercase and catches it no matter what?

Ex;

@app.message('keyword')
def reply_in_thread(body: dict, say: Say):
event = body ["event"]
thread_ts = event.get("thread_ts", None) or event["ts"]
say(text="Hello! For this request please submit a ticket.", 
thread_ts=thread_ts)