Add nested_update.in_place argument (#13)

* Add nested_update.in_place argument

* Update README.rst and tests

README.rst

@@ -14,11 +14,11 @@ A document in this case is a a mixture of Python dictionary and list objects typ
   Returns a `list` of matching values.
 
 *nested_update:*
-  Given a document, find all occurances of the given key and update the value.
+  Given a document, find all occurences of the given key and update the value
-  Returns a copy of the document.
+  By default, returns a copy of the document. To mutate the original one instead - please specify the `in_place=True` argument.
 
 *nested_delete:*
-  Given a document, find all occurances of the given key and delete it.
+  Given a document, find all occurrences of the given key and delete it.
   Returns a copy of the document.
 
 *get_all_keys:*

nested_lookup/lookup_api.py

@@ -28,9 +28,10 @@ def _nested_delete(document, key):
     return document
 
 
-def nested_update(document, key, value):
+def nested_update(document, key, value, in_place=False):
-    duplicate = copy.deepcopy(document)
+    if not in_place:
-    return _nested_update(document=duplicate, key=key, value=value)
+        document = copy.deepcopy(document)
+    return _nested_update(document=document, key=key, value=value)
 
 
 def _nested_update(document, key, value):

test_lookup_api.py

@@ -103,6 +103,19 @@ class TestNestedUpdate(BaseLookUpApi):
             result, nested_update(self.sample_data1, 'build_version', 'Test1')
         )
 
+    def test_in_place(self):
+        result = {
+            "build_version": "Test1",
+            "os_details": {
+                "product_version": '10.13.6',
+                "build_version": 'Test1'
+            },
+            "name": 'Test',
+            "date": 'YYYY-MM-DD HH:MM:SS'
+        }
+        nested_update(self.sample_data1, 'build_version', 'Test1', in_place=True)
+        self.assertEqual(result, self.sample_data1)
+
     def test_sample_data2(self):
         result = {
             "hardware_details": {