diff --git a/srcxray.py b/srcxray.py
index fdf3bc8..4d0851e 100755
--- a/srcxray.py
+++ b/srcxray.py
@@ -1158,6 +1158,9 @@ def doxygen(*input):
 
 
 def doxygen_xml(a):
+    '''
+    Arg: <xml directory generated by doxygen> - extracts call graph
+    '''
     g = my_graph()
     for x in list(glob.glob(os.path.join(a, "*.xml")) + [a]):
         # print(x)