python-3.6.zip added from Github

README.cosmo contains the necessary links.

third_party/python/Lib/test/test_openpty.py

@@ -0,0 +1,21 @@
+# Test to see if openpty works. (But don't worry if it isn't available.)
+
+import os, unittest
+
+if not hasattr(os, "openpty"):
+    raise unittest.SkipTest("os.openpty() not available.")
+
+
+class OpenptyTest(unittest.TestCase):
+    def test(self):
+        master, slave = os.openpty()
+        self.addCleanup(os.close, master)
+        self.addCleanup(os.close, slave)
+        if not os.isatty(slave):
+            self.fail("Slave-end of pty is not a terminal.")
+
+        os.write(slave, b'Ping!')
+        self.assertEqual(os.read(master, 1024), b'Ping!')
+
+if __name__ == '__main__':
+    unittest.main()