How does the heat pump work in a Toyota Prius Prime plug-in hybrid?

2017 Toyota Prius Prime PremiumThe challenge of reducing the energy used by traditional heating systems in battery-electric and plug-in hybrid cars is one automakers still grapple with today. Reduced battery range in cold temperatures, combined with batteries working overtime to heat the cabin, can produce drastic declines in EPA-estimated range figures. The Toyota Prius Prime...