How is a government formed post-election?

An election gives us the numbers, but it doesn't necessarily give us a government. Under MMP, what happens next can involve days or even weeks of negotiation as parties work out whether they have the numbers to govern, and on what terms. So how does that process actually work, and what rules are everyone playing by? Dr Dean Knight is an expert in constitutional law at Te Herenga Waka Victoria University of Wellington - he joins Emile for a chat.