Fix #702

tests/all.test

@@ -503,6 +503,10 @@ map(add)
 [[], [1,2,3], ["a","b","c"], [[3],[4,5],[6]], [{"a":1}, {"b":2}, {"a":3}]]
 [null, 6, "abc", [3,4,5,6], {"a":3, "b": 2}]
 
+map_values(.+1)
+[0,1,2]
+[1,2,3]
+
 #
 # User-defined functions
 # Oh god.