Remove the battery widget if there is no battery

.config/qtile/config.py

@@ -51,6 +51,9 @@ class ConfigWrapper:
         self._add_key(access_key, lazy.group[name].toscreen())
         self._add_key(access_key, lazy.window.togroup(name), extra_mod='shift')
 
+    def _has_battery(self):
+        return len(glob('/sys/class/power_supply/BAT*')) > 0
+
     def set_wallpaper(self):
         images = glob(os.path.expanduser('~/pictures/wallpapers/enabled/*'))
         if images:
@@ -117,10 +120,7 @@ class ConfigWrapper:
         )
 
     def set_screens(self):
-        screens = [
-            Screen(
-                top=bar.Bar(
-                    [
+        widgets = [
             widget.GroupBox(),
             widget.Prompt(),
             widget.WindowName(),
@@ -133,9 +133,12 @@ class ConfigWrapper:
             widget.MemoryGraph(**self.graph_params('#CFCE44')),
             widget.CPUGraph(**self.graph_params('#96AECF')),
             widget.Clock(format=self.date_format),
-                    ],
-                    30,
-                ),
+        ]
+        if not self._has_battery():
+            widgets = [w for w in widgets if not isinstance(w, widget.Battery)]
+        screens = [
+            Screen(
+                top=bar.Bar(widgets, 30)
             ),
         ]
         return screens