testcode for doc/faq.txt

doc/faq.txt

@@ -120,7 +120,10 @@ the function was compiled.
 
 For example, replace the following
 
-.. code-block:: python
+.. testcode:: faster
+
+    import theano
+    from theano import function
 
     x = theano.tensor.scalar('x')
     f = function([x], x + 1.)
@@ -128,7 +131,11 @@ For example, replace the following
 
 with
 
-.. code-block:: python
+.. testcode:: faster
+
+    import numpy
+    import theano
+    from theano import function
 
     x = theano.tensor.scalar('x')
     f = function([x], x + 1.)