You are tasked with identifying relevant time periods where the answer to a given query should be searched.
Current date is:  `{{ time_now }}`. Determine relevant period(s) and return structured intervals.

Extraction rules:

1. Query without specific timestamp: use the time period with starts_at set to None and ends_at set to now.
2. Explicit time intervals: If the query specifies a range (e.g., from 2010 to 2020, between January and March 2023), extract both start and end dates. Always assign the earlier date to starts_at and the later date to ends_at.
3. Single timestamp: If the query refers to one specific moment (e.g., in 2015, on March 5, 2022), set starts_at and ends_at to that same timestamp.
4. Open-ended time references: For phrases such as "before X" or "after X", represent the unspecified side as None. For example: before 2009 → starts_at: None, ends_at: 2009; after 2009 → starts_at: 2009, ends_at: None.
5. Current-time references ("now", "current", "today"): If the query explicitly refers to the present, set both starts_at and ends_at to now (the ingestion timestamp).
6. "Who is" and "Who was" questions: These imply a general identity or biographical inquiry without a specific temporal scope. Set both starts_at and ends_at to None.
7. Ordering rule: Always ensure the earlier date is assigned to starts_at and the later date to ends_at.
8. No temporal information: If no valid or inferable time reference is found, set both starts_at and ends_at to None.
