back button goes to map screen on other two

main.py

@@ -1,6 +1,7 @@
 from plyer import gps
 from kivy.app import App
 from kivy.clock import Clock
+from kivy.core.window import Window
 from kivy.properties import DictProperty, NumericProperty, StringProperty
 from kivy.clock import mainthread
 from kivy.utils import platform
@@ -24,11 +25,28 @@ class MapScreen(Screen):
 
 
 class CompassScreen(Screen):
-    pass
+    def __init__(self, **kwargs):
+        super(CompassScreen, self).__init__(**kwargs)
+        Window.bind(on_keyboard=self.android_back_click)
+        
+    def android_back_click(self, window, key, *largs):
+        if key == 27 and self.parent is not None:            
+            self.parent.current='map'
+            return True    
+
 
 
 class SettingsScreen(Screen):
-    pass
+    def __init__(self, **kwargs):
+        super(SettingsScreen, self).__init__(**kwargs)
+        Window.bind(on_keyboard=self.android_back_click)
+
+    def android_back_click(self, window, key, *largs):
+        
+        if key == 27 and self.parent is not None:
+            self.parent.current='map'
+            return True    
+
 
 
 class FlockompassApp(App):
@@ -199,7 +217,6 @@ class FlockompassApp(App):
         
         screen_manager.add_widget(self.cs)
 
-
         self.ss = SettingsScreen(name='settings')
         screen_manager.add_widget(self.ss)