Cairo things to remember:

1. Cairo memory is immutable, once you write the value of a memory cell, this cell cannot change in the future. Hence, we replace loops with recurssion.
2. Loops are possible but we cannot call functions inside a loop and they are more complicated to implement.

"Cairo memory is immutable, which means that once a value was written to a memory cell, it cannot change."

Cairo does not have a built in less than '<' operator.