How to define a custom load shape in Locust for complex user load pattern?

Question

I'm trying to create a complex user load pattern in Locust and need help defining a custom load shape. Here is the scenario I want to implement:

User load pattern:

• Ramp-Up to 5000 Users in 2 minutes
• Maintain 5000 Users for 1 minute
• Ramp-Up to 8000 Users in 5 minutes
• Maintain 8000 Users for 3 minutes
• Ramp-Up to 12000 Users in 2 minutes
• Maintain 12000 Users for 4 minutes
• Ramp-Up to 18000 Users in 3 minutes
• Maintain 18000 Users for 5 minutes
• Ramp-Down to 10000 Users in 5 minutes
• Maintain 10000 Users for 5 minutes
• Ramp-Up to 20000 Users in 5 minutes
• Maintain 20000 Users for 10 minutes
• Ramp-Down to 5000 Users in 2 minutes
• Maintain 5000 Users for 10 minutes

Total Duration: 1 hour (60 minutes)

I understand that I need to use a custom LoadTestShape class to define this pattern. Could someone explain how to structure the tick method to accurately follow this user load pattern? What would be the best approach to implement this in Locust?