added credits to @gwidion

25-class-metaprog/tinyenums/microenum.py

@@ -1,3 +1,6 @@
+# This is an implementation of an idea by João S. O. Bueno (@gwidion)
+# shared privately with me, with permission to use in Fluent Python 2e.
+
 """
 Testing ``AutoFillDict``::
 

25-class-metaprog/tinyenums/nanoenum.py

@@ -1,3 +1,6 @@
+# This is a simplification of an idea by João S. O. Bueno (@gwidion)
+# shared privately with me, with permission to use in Fluent Python 2e.
+
 """
 Testing ``KeyIsValueDict``::