You're seeing just the function
set_topic, go back to Slack.Web.Groups module for more information.
Sets the topic for a private channel.
channel- Private channel to set the topic of
topic- The new topic ex:
Errors the API can return:
channel_not_found- Value passed for
is_archived- Private group has been archived
too_long- Topic was longer than 250 characters.
user_is_restricted- Setting the topic is a restricted action.