fix doc warning

2ddfa2ea · Arnaud Bergeron · Brandon T. Willard · ad2d94b8 · 2ddfa2ea
--- a/doc/extending/extending_theano.txt
+++ b/doc/extending/extending_theano.txt
@@ -791,7 +791,7 @@ implementation.
 It takes an optional :func:`infer_shape` parameter that must have this
 signature:

-.. code-block:: python
+.. code-block::

    def infer_shape(node, input_shapes):
        # ...