remove flake8 errors

theano/tensor/tests/test_assert_op_gradient.py

@@ -4,10 +4,11 @@ import theano
 import theano.tensor as T
 from theano.tensor.opt import Assert
 
+
 def test_assert_op_gradient():
     x = T.vector('x')
     assert_op = Assert()
-    cost = T.sum(assert_op(x, x.size<2))
+    cost = T.sum(assert_op(x, x.size < 2))
     grad = T.grad(cost, x)
     func = theano.function([x], grad)