Add distinct_list aggregator to visidatarc

visidatarc

@@ -18,6 +18,11 @@ def avgdiff(values):
 
 aggregator('avgdiff', avgdiff)
 
+def distinct_list(values):
+    return [x for x in set(values)]
+
+aggregator('distinct_list', distinct_list)
+
 def logtime(val):
     a=str(val)
     a=a.strip()