Change the Persona's set of anti-links.
It's preferred to call this rather than setting AntiLinkable.anti_links directly, as this method gives error notification and will only return once the anti-links have been written to the relevant backing store (or the operation's failed).
It should be noted that IndividualAggregator.link_personas and IndividualAggregator.unlink_individual will modify the anti-links sets of the personas they touch, in order to remove and add anti-links, respectively. It is expected that these IndividualAggregator methods will be used to modify anti-links indirectly, rather than calling AntiLinkable.change_anti_links directly.
the new set of anti-links from this persona
if setting the anti-links failed