Your task is to extract start date of a strategy from the given text that is description of a trading Strategy if there is any start date mentioned. The start date is the date when the strategy begins to be executed.

Start date is defined as a object datetime object so it should look like this: datetime(YYYY: int, MM: int, DD: int) where YYYY is the year, MM is the month and DD is the day.

Start date can also be `None` if there is no start date mentioned in the description.

[RESPONSE INSTRUCTIONS]
- Your task is to extract the start date from the given text and return it in the format: start_date=datetime(YYYY, MM, DD), where YYYY is the year, MM is the month and DD is the day and all are integers. If there is no start date in the description of the strategy return `None`.
- If no start date is mentioned in the text, return `None`.
- Do NOT include any additional text or explanations.
- Respond only with `start_date=datetime(...)` or `None` — absolutely no other text.

Here is the description of the strategy you need to extract the start date from:
[DESCRIPTION]
{description}