docs: python bindings

* Updated the Cython example code slightly, along with the
  corresponding explanation.

doc/gpgme-python-howto.texi

@@ -2122,6 +2122,7 @@ pubnum = len(publist)
 print("""
     Number of secret keys:  @{0@}
     Number of public keys:  @{1@}
+
 """.format(secnum, pubnum))
 @end example
 
@@ -2172,7 +2173,10 @@ On the other hand it ran in nearly half the time; taking 6 minutes and
 which the CPython script alone took.
 
 The @samp{keycount.pyx} and @samp{setup.py} files used to generate this example
-have been added to the @samp{examples/howto/advanced/cython/} directory.
+have been added to the @samp{examples/howto/advanced/cython/} directory
+The example versions include some additional options to annotate the
+existing code and to detect Cython's use.  The latter comes from the
+@uref{http://docs.cython.org/en/latest/src/tutorial/pure.html#magic-attributes-within-the-pxd, Magic Attributes} section of the Cython documentation.
 
 @node Miscellaneous work-arounds
 @chapter Miscellaneous work-arounds

lang/python/docs/gpgme-python-howto.org

@@ -2027,6 +2027,7 @@ pubnum = len(publist)
 print("""
     Number of secret keys:  {0}
     Number of public keys:  {1}
+
 """.format(secnum, pubnum))
 #+END_SRC
 
@@ -2077,7 +2078,10 @@ On the other hand it ran in nearly half the time; taking 6 minutes and
 which the CPython script alone took.
 
 The =keycount.pyx= and =setup.py= files used to generate this example
-have been added to the =examples/howto/advanced/cython/= directory.
+have been added to the =examples/howto/advanced/cython/= directory
+The example versions include some additional options to annotate the
+existing code and to detect Cython's use.  The latter comes from the
+[[http://docs.cython.org/en/latest/src/tutorial/pure.html#magic-attributes-within-the-pxd][Magic Attributes]] section of the Cython documentation.
 
 
 * Miscellaneous work-arounds

lang/python/examples/howto/advanced/cython/keycount.pyx

@@ -1,3 +1,6 @@
+from __future__ import absolute_import
+
+import cython
 import gpg
 
 c = gpg.Context()
@@ -10,7 +13,14 @@ secnum = len(seclist)
 publist = list(pubkeys)
 pubnum = len(publist)
 
+if cython.compiled is True:
+    cc = "Powered by Cython compiled C code."
+else:
+    cc = "Powered by Python."
+
 print("""
     Number of secret keys:  {0}
     Number of public keys:  {1}
-""".format(secnum, pubnum))
+
+  {2}
+""".format(secnum, pubnum, cc))

lang/python/examples/howto/advanced/cython/setup.py

@@ -2,5 +2,5 @@ from distutils.core import setup
 from Cython.Build import cythonize
 
 setup(
-    ext_modules = cythonize("keycount.pyx")
+    ext_modules = cythonize("keycount.pyx", annotate=True)
 )