only call extend on W_Parameterization
only call extend on W_Parameterization

vishesh/pycket,samth/pycket,krono/pycket,magnusmorton/pycket,magnusmorton/pycket,pycket/pycket,vishesh/pycket,vishesh/pycket,pycket/pycket,samth/pycket,cderici/pycket,magnusmorton/pycket,cderici/pycket,samth/pycket,krono/pycket,pycket/pycket,krono/pycket,cderici/pycket