You will see like
import math # %% user data x = 3 y = 4 # %% main loop for i in range(5): x += y
The code cells allow running sections of code in an IDE without the need to constantly set/unset breakpoints in the IDE. They also catch the eye of developers to delineate logical blocks of code in the algorithm.
We encourage the use of code cell syntax, even if you don't use them in the IDE directly, as the IDE will highlight sections of code to visibly delineate these separate parts of the algorithm.