--- a/dataimport.py	Tue Jul 19 13:50:56 2016 +0200
+++ b/dataimport.py	Tue Jul 19 12:47:28 2016 +0200
@@ -95,6 +95,7 @@
     else:
         f = stream_or_filename
         f.seek(0)
+    i = 0  # useful is f is an empty file
     for i, line in enumerate(f):
         pass
     f.seek(0)