diff --git a/style_mixing.py b/style_mixing.py
index c47bebbc4..a52757f3f 100755
--- a/style_mixing.py
+++ b/style_mixing.py
@@ -24,7 +24,9 @@
 
 def num_range(s: str) -> List[int]:
     '''Accept either a comma separated list of numbers 'a,b,c' or a range 'a-c' and return as a list of ints.'''
-
+    
+    if type(s) is type([]):
+        return s
     range_re = re.compile(r'^(\d+)-(\d+)$')
     m = range_re.match(s)
     if m: