diff -r 15c95d3fcfd8 -r f0a6bf48b05e geometry.py
--- a/geometry.py	Wed Jun 05 00:33:50 2019 +0300
+++ b/geometry.py	Sat Jun 08 01:32:25 2019 +0300
@@ -1,6 +1,9 @@
 def degree_rep(angle):
     from math import degrees
-    return '%.2f°' % degrees(angle)
+    try:
+        return '%.2f°' % degrees(angle)
+    except TypeError:
+        return angle
 
 def position_vector(vertex):
     assert isinstance(vertex, Vertex)