def participation_policy_changed(ob, event):
""" Move all the existing users to a new group """
workspace = IWorkspace(ob)
old_group_name = workspace.group_for_policy(event.old_policy)
old_group = api.group.get(old_group_name)
for member in old_group.getAllGroupMembers():
groups = workspace.get(member.getId()).groups
groups -= set([event.old_policy.title()])
groups.add(event.new_policy.title())
