Fix d3viz multi-level tag.

theano/d3viz/formatting.py

@@ -292,7 +292,10 @@ def var_tag(var):
     """Parse tag attribute of variable node."""
     tag = var.tag
     if hasattr(tag, 'trace') and len(tag.trace) and len(tag.trace[0]) == 4:
-        path, line, _, src = tag.trace[0]
+        if isinstance(tag.trace[0][0], (tuple, list)):
+            path, line, _, src = tag.trace[0][-1]
+        else:
+            path, line, _, src = tag.trace[0]
         path = os.path.basename(path)
         path = path.replace('<', '')
         path = path.replace('>', '')