Function iso8601_python 

pub fn iso8601_python(dt: &DateTime<Utc>) -> String

Format a UTC timestamp the way Python’s datetime.isoformat() does for tz-aware UTC: YYYY-MM-DDThh:mm:ss[.ffffff]+00:00. Microsecond precision is preserved when non-zero. The +00:00 suffix (not Z) is required by SPEC §4 clause 7.