13.9. OOP Architecture

13.9.1. Boxes and Arrows

13.9.2. UML

• Unified Modeling Language

13.9.3. UML Class Diagram

13.9.4. UML Sequence Diagram

13.9.5. Mermaid

• mermaid - Markdown extension

```mermaid
classDiagram
      Animal <|-- Duck
      Animal <|-- Fish
      Animal <|-- Zebra
      Animal : +int age
      Animal : +String gender
      Animal: +isMammal()
      Animal: +mate()

      class Duck{
          +String beakColor
          +swim()
          +quack()
      }

      class Fish{
          -int sizeInFeet
          -canEat()
      }

      class Zebra{
          +bool is_wild
          +run()
      }
```