Removed unnecessary imports.

theano/sparse/opt.py

@@ -4,13 +4,12 @@ import theano
 import numpy
 from theano import gof, scalar, tensor
 from theano.tensor import blas
-from theano.sparse import (CSC, CSR, csm_properties, Remove0,
+from theano.sparse import (CSC, CSR, csm_properties,
                            register_specialize,
                            csm_grad, usmm)
 from theano.sparse import basic as sparse
 
-from basic import _is_sparse_variable
-
+_is_sparse_variable = sparse._is_sparse_variable
 
 # This is tested in tests/test_opt.py:test_local_csm_properties_csm
 @gof.local_optimizer([csm_properties])