The article discusses how to assess if a country's debt is sustainable, even when considering the possibility of the country defaulting on its debt. The researchers found that the amount of debt a country can handle without defaulting depends on how much of the debt can be recovered after a default. They also found that a country's debt can still be sustainable after a default if the amount of debt that is forgiven (haircut) is large enough. Additionally, the researchers explain how countries can end up defaulting on their debt multiple times in a row.