Index: extending.rst
===================================================================
--- extending.rst	(revision 82116)
+++ extending.rst	(working copy)
@@ -231,7 +231,26 @@
 We discuss the use of PyMODINIT_FUNC as a function return type later in this
 sample.
 
+The :exc:`spam.error` exception can be raised in your extension module using
+a call to :cfunc:`PyErr_SetString` as shown below::
 
+   static PyObject *
+   spam_system(PyObject *self, PyObject *args)
+   {
+       const char *command;
+       int sts;
+
+       if (!PyArg_ParseTuple(args, "s", &command))
+           return NULL;
+       sts = system(command);
+       if (sts < 0)
+         {
+	   PyErr_SetString (SpamError, "System command failed");
+	   return NULL;
+	 }
+       return Py_BuildValue("i", sts);
+   }
+
 .. _backtoexample:
 
 Back to the Example