python: typing: 3.5.3.0 -> 3.6.4

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

@@ -0,0 +1,29 @@
+{ lib, buildPythonPackage, fetchPypi, pythonOlder, isPy3k, python }:
+
+let
+  testDir = if isPy3k then "src" else "python2";
+
+in buildPythonPackage rec {
+  pname = "typing";
+  version = "3.6.4";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "d400a9344254803a2368533e4533a4200d21eb7b6b729c173bc38201a74db3f2";
+  };
+
+  # Error for Python3.6: ImportError: cannot import name 'ann_module'
+  # See https://github.com/python/typing/pull/280
+  doCheck = pythonOlder "3.6";
+
+  checkPhase = ''
+    cd ${testDir}
+    ${python.interpreter} -m unittest discover
+  '';
+
+  meta = with lib; {
+    description = "Backport of typing module to Python versions older than 3.5";
+    homepage = https://docs.python.org/3/library/typing.html;
+    license = licenses.psfl;
+  };
+}