# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1509136032 -7200
# Node ID 9cabf3cd6a38c4e11028130ece06a96417a16ad5
# Parent  b4ffc23dd9c8b921d964c04603245983319d9370# Parent  683059dc2e7bdd2d32cf98ff4048ba9d35c4617e
Merged changes from the default branch.

diff -r b4ffc23dd9c8 -r 9cabf3cd6a38 imiptools/data.py
--- a/imiptools/data.py	Fri Oct 27 00:44:53 2017 +0200
+++ b/imiptools/data.py	Fri Oct 27 22:27:12 2017 +0200
@@ -1132,7 +1132,7 @@
 uri_value = get_uri
 
 def uri_values(values):
-    return map(get_uri, values)
+    return values and map(get_uri, values)
 
 def uri_dict(d):
     return dict([(get_uri(key), value) for key, value in d.items()])
@@ -1141,7 +1141,7 @@
     return get_uri(item[0]), item[1]
 
 def uri_items(items):
-    return [(get_uri(value), attr) for value, attr in items]
+    return items and [(get_uri(value), attr) for value, attr in items]
 
 # Operations on structure data.