Implemented Context.push().

pystache/context.py

@@ -136,4 +136,7 @@ class Context(object):
 
         return default
 
+    def push(self, item):
+        self._stack.append(item)
+
 

tests/test_context.py

@@ -217,3 +217,15 @@ class ContextTestCase(TestCase):
         context = Context({"fuzz": "buzz"}, {"foo": "bar"})
         self.assertEquals(context.get("fuzz"), "buzz")
 
+    def test_push(self):
+        """
+        Test push().
+
+        """
+        key = "foo"
+        context = Context({key: "bar"})
+        self.assertEquals(context.get(key), "bar")
+
+        context.push({key: "buzz"})
+        self.assertEquals(context.get(key), "buzz")
+