Our users don't practice the habit to assign Topics to / #hashtags within their posts. As such we want to assign 'Topics' to the Yammer posts (regardless in which group the post is generated) whenever a new Update/Announcement is posted. The Flow would be triggered on creation of a new update/announcement and would assign dedicated 'Topics' based upon a list of (hardcoded) keywords defined in the flow itself, whenever the keyword would appear as text in the posted message.