from trac.perm import PermissionSystem # initialize PermissionSystem permission_system = PermissionSystem(env) # set a permission for a user permission_system.grant_permission(username, 'TICKET_CREATE') # remove a permission from a user permission_system.revoke_permission(username, 'TICKET_MODIFY') # check if a user has a certain permission if permission_system.check_permission('TICKET_VIEW', username): # do somethingIn the above code examples, we first initialize the PermissionSystem object with the Trac environment. We then use the `grant_permission` and `revoke_permission` methods to add or remove permissions for a user. Lastly, we use the `check_permission` method to check if a user has a certain permission. The package library for this Python package is Trac.