Attempt to use coverage to quantify how many of the CONDITIONAL_NAMES we really use (#3763)

* Attempt to use coverage to quantify how many of the CONDITIONAL_NAMES we really use

* rewrite file to improve coverage

* Write it this way so we can use line coverage

* lost this one :-(

* fix comment and flake8

* update the docs as well

* flake8
diff --git a/docs/development/c-bindings.rst b/docs/development/c-bindings.rst
index 43ec4d8..8a9bb6d 100644
--- a/docs/development/c-bindings.rst
+++ b/docs/development/c-bindings.rst
@@ -167,15 +167,22 @@
 Finally, add an entry to ``CONDITIONAL_NAMES`` with all of the things
 you want to conditionally export::
 
-    CONDITIONAL_NAMES = {
-        ...
-        "Cryptography_HAS_QUANTUM_TRANSMOGRIFICATION": [
+    def cryptography_has_quantum_transmogrification():
+        return [
             "QM_TRANSMOGRIFICATION_ALIGNMENT_LEFT",
             "QM_TRANSMOGRIFICATION_ALIGNMENT_RIGHT",
-            "QM_transmogrify"
+            "QM_transmogrify",
         ]
+
+
+    CONDITIONAL_NAMES = {
+        ...
+        "Cryptography_HAS_QUANTUM_TRANSMOGRIFICATION": (
+            cryptography_has_quantum_transmogrification
+        ),
     }
 
+
 Caveats
 ~~~~~~~