Add interfaces for weather forecasting.

Co-Authored-By: os222

src/main/java/ic/doc/WeatherForecast.java

@@ -0,0 +1,7 @@
+package ic.doc;
+
+public interface WeatherForecast {
+  String summary();
+
+  int temperature();
+}

src/main/java/ic/doc/WeatherForecaster.java

@@ -0,0 +1,5 @@
+package ic.doc;
+
+public interface WeatherForecaster {
+    WeatherForecast forecastFor(WeatherRegion region, Weekday day);
+}

src/main/java/ic/doc/WeatherRegion.java

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+package ic.doc;
+
+public enum WeatherRegion {
+  BIRMINGHAM,
+  EDINBURGH,
+  GLASGOW,
+  LONDON,
+  MANCHESTER,
+  NORTH_ENGLAND,
+  SOUTH_WEST_ENGLAND,
+  SOUTH_EAST_ENGLAND,
+  WALES
+}

src/main/java/ic/doc/Weekday.java

@@ -0,0 +1,11 @@
+package ic.doc;
+
+public enum Weekday {
+  MONDAY,
+  TUESDAY,
+  WEDNESDAY,
+  THURSDAY,
+  FRIDAY,
+  SATURDAY,
+  SUNDAY
+}