Function next_cds_imm_date 

pub fn next_cds_imm_date(today: NaiveDate) -> NaiveDate

The next CDS-IMM date strictly after today — the 20th of the next March / June / September / December (calendar date, not business-day adjusted). A CDS-IMM date rolls to the following one, as next_semi_annual_roll_date does.

Panics

Only if today sits in the last year chrono can represent, where rolling to the following March leaves its range. No market date is near that bound.