GetThreadTimestamp uses conversations.history to retrieve the timestamp for either the message or the thread parent message, if one exists.

InvalidCommand returns a formatted error for improper flag usage with a CLI command.

InvalidFlagValue returns a formatted error for improper flag usage.

ParsePayload takes request body and parses payload parameter into a usable string.

Respond takes response text and posts it to the response url.

RespondOK responds to a request with Content-Type: application/json and 200 OK meant for acknowledging incoming Slack requests.

SendError responds to a user interaction with an error.

Unique takes string slice and removes unique elements.