How to check the list of absences with a Slack command?

/calamari absences dates

This command will show you who was or is going to be absent. 

Note:
Self-explanatory examples:

• /calamari absences today

• /calamari absences yesterday

• /calamari absences this week

• /calamari absences last week

• /calamari absences next week

• /calamari absences next month