structure image updated
# Upgrade mechanism
->Use [structure image](https://drive.google.com/file/d/1tsgcS3m5poEL1A3B27dKpjUgw1V8XY2R/view?usp=sharing) for better understanding
+This is an image of the dependencies structure.
+Use it for a better understanding.
+![](https://i.imgur.com/nXRKt8a.png)
## Contracts and interfaces
