Define properties correctly in surface3d example
@@ -48,11 +48,11 @@ class Surface3d(LayoutDOM):
# The data will actually be stored in the ColumnDataSource, but these
# properties let us specify the *name* of the column that should be
# used for each field.
- x = String
+ x = String()
- y = String
+ y = String()
- z = String
+ z = String()
# Any of the available vis.js options for Graph3d can be set by changing
# the contents of this dictionary.
