Your Lambda function might execute twice. Be prepared!

demo1: Something is wrong here
demo2: Twitter like status updates (broken: mixed and missing updates)
demo3: Twitter like status updates - Status update creation time as an input (broken: missing updates)
demo4: Twitter like status updates - Previous status update as an input (broken: missing updates)
demo5: Twitter like status updates - Use Kinesis Data Stream in between
demo6: Twitter like status updates - Use Kinesis Data Stream in between with sequence numbers (safe)
demo7: TODO
demo8: at-most-once Slack message
demo9: at-least-once Slack message

Prepare demos

cp env.example.sh env.sh
# edit as needed
source env.sh

Each demo has a deploy.sh script that you can use to create/update the demo stack.