pythonPackages: Add version and pname attributes to packages

pkgs/development/python-modules/webencodings/default.nix

@@ -4,10 +4,9 @@
 , pytest
 }:
 
-let
+buildPythonPackage rec {
   pname = "webencodings";
   version = "0.5.1";
-in buildPythonPackage rec {
   name = "${pname}-${version}";
 
   src = fetchurl {
@@ -26,4 +25,4 @@ in buildPythonPackage rec {
     homepage = https://github.com/SimonSapin/python-webencodings;
     license = lib.licenses.bsd3;
   };
-}
+}