erajp(Some (), erajp:: to_era_from_year (2019)); a day to Japanese era extern crate chrono ; use chrono :: prelude :: * ; let = Local :: (); assert_eq !(Some (), erajp:: to_era_from_year (2019)); a day to Japanese era extern crate chrono ; use chrono :: prelude :: * ; let = Local :: (); assert_eq !