What is the parameter i after declaring the lambda function?

Question

Python

Hello, I have some questions while learning lambda expressions. What is the parameter i after declaring the lambda function?

points = [{ 'x' : 2, 'y' : 3 }, { 'x' : 4, 'y' : 1 }]
points.sort(key=lambda i : i['y'])
print(points)

Answer 1

Nothing after the announcement.
A function in python is an object of the first kind, before it is called, the arguments are not defined and the context is not created, but the context is created with each call.