reuse the quarto_theme if already defined

src/resources/jupyter/lang/python/setup.py

@@ -49,16 +49,17 @@
     options.paging = False
   except Exception:
     pass
-
+  
   try:
     import altair as alt
 
     # By default, dashboards will have container sized
     # vega visualizations which allows them to flow reasonably
-    def quarto_dashboard_theme(*args, **kwargs):
-      return dict(width = 'container', height= 'container')
-    alt.themes.register('quarto-dashboard-theme', quarto_dashboard_theme)
-    alt.themes.enable('quarto-dashboard-theme')
+    if 'quarto-dashboard-theme' not in alt.themes.names():
+      def quarto_dashboard_theme(*args, **kwargs):
+        return dict(width = 'container', height= 'container')
+      alt.themes.register('quarto-dashboard-theme', quarto_dashboard_theme)
+      alt.themes.enable('quarto-dashboard-theme')
 
   except Exception:
     pass