Python Flask Developer for Payment System，要求熟悉中文，会中文沟通交流

I need a skilled Python backend engineer, particularly one with deep understanding and experience in Flask framework, Redis, and MongoDB. The project involves creating a robust payment processing system with the following critical functionalities:

- Tracking of transaction history
- Integration with multiple payment gateways
- Implementing user authentication and security measures
- Seamless integration with various third-party payment systems, specifically PayPal, Stripe, and Square

Prior experience in developing payment systems is highly preferred. You should also be well-versed in sharding with MongoDB.

Ideal Skills:
- Python, specifically with Flask framework
- Experience with Redis and MongoDB (sharding)
- Prior experience in developing payment systems
- Expertise in integrating with PayPal, Stripe, and Square
- Strong knowledge in implementing user authentication and security measures
要求熟悉中文，会中文沟通交流