Fix intern() Py3 compat

loopy/symbolic.py

@@ -25,6 +25,8 @@ THE SOFTWARE.
 """
 
 
+from six.moves import intern
+
 from pytools import memoize, memoize_method, Record
 import pytools.lex
 
@@ -1046,6 +1048,4 @@ class AccessRangeMapper(WalkMapper):
 
 # }}}
 
-
-
 # vim: foldmethod=marker