PEP8 fixes to tensor.roll.

theano/tensor/basic.py

@@ -4290,6 +4290,7 @@ def join(axis, *tensors):
 pprint.assign(lambda pstate, r: r.owner and isinstance(r.owner.op, Join),
               printing.FunctionPrinter('join'))
 
+
 def roll(x, shift, axis=0):
     """
     Convenience function to roll `TensorType`s along the given axis.
@@ -4313,11 +4314,13 @@ def roll(x, shift, axis=0):
                   [allslice] * (x.ndim - axis - 1))
     # List of slices describing the back half [:, :, :shift, :]
     end_slice = slice(0, -shift)
-    end_list = [allslice]*axis + [end_slice] + [allslice]*(x.ndim-axis-1)
+    end_list = ([allslice] * axis + [end_slice] +
+                [allslice] * (x.ndim - axis - 1))
     return join(axis,
                 Subtensor(front_list)(x),
                 Subtensor(end_list)(x))
 
+
 @constructor
 def shape_padleft(t, n_ones=1):
     """Reshape `t` by left-padding the shape with `n_ones` 1s