func strftime(format: string; st: Some_struct_time_tuple): string

func strftime(format: string; st: struct_time): string {....raises: [], tags: [],
    forbids: [].}

func strftime[S](format: S; st: struct_time): S

proc strptime(s: string; f: string): struct_time {.
    ...raises: [ValueError, TimeParseError, TimeFormatParseError],
    tags: [TimeEffect], forbids: [].}