Ch2Weather first version

Ch2Weather/Exercise1.mermaid

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+classDiagram
+    class WeatherData {
+        getTemperature()
+        getHumidity()
+        getPressure()
+        measurementsChanged()
+
+        subscribe(observer: IWeatherObserver)
+        unsubscribe(observer: IWeatherObserver)
+        notify(data: WeatherRecord)
+    }
+    class WeatherRecord {
+        f32 temperature
+        f32 humidity
+        f32 pressure
+    }
+    class IWeatherObserver {
+        update(data: WeatherRecord)
+    }
+    class IWeatherSubject {
+        subscribe(observer: IWeatherObserver)
+        unsubscribe(observer: IWeatherObserver)
+        notify(data: WeatherRecord)
+    }
+    class WeatherScreen1 {
+        update(data: WeatherRecord)
+        draw()
+    }
+    IWeatherSubject <|.. WeatherData
+    IWeatherObserver <|.. WeatherScreen1
+    IWeatherObserver <-- IWeatherSubject : observers
+    WeatherData <-- WeatherScreen1 : Subjects
+    IWeatherObserver .. IWeatherSubject
+    class IDisplayElement {
+        draw()
+    }
+    IDisplayElement <|.. WeatherScreen1
+