Example of refactoring using rope library.

tools/telemetry/third_party/rope/rope/contrib/changestack.py

Index: tools/telemetry/third_party/rope/rope/contrib/changestack.py
diff --git a/tools/telemetry/third_party/rope/rope/contrib/changestack.py b/tools/telemetry/third_party/rope/rope/contrib/changestack.py
new file mode 100644
index 0000000000000000000000000000000000000000..70f2271f7c640229788823cdda7c6df18ea787de
--- /dev/null
+++ b/tools/telemetry/third_party/rope/rope/contrib/changestack.py
@@ -0,0 +1,52 @@
+"""For performing many refactorings as a single command
+
+`changestack` module can be used to perform many refactorings on top
+of each other as one bigger command.  It can be used like::
+
+  stack = ChangeStack(project, 'my big command')
+
+  #..
+  stack.push(refactoring1.get_changes())
+  #..
+  stack.push(refactoring2.get_changes())
+  #..
+  stack.push(refactoringX.get_changes())
+
+  stack.pop_all()
+  changes = stack.merged()
+
+Now `changes` can be previewed or performed as before.
+"""
+
+from rope.base import change
+
+
+class ChangeStack(object):
+
+    def __init__(self, project, description='merged changes'):
+        self.project = project
+        self.description = description
+        self.stack = []
+
+    def push(self, changes):
+        self.stack.append(changes)
+        self.project.do(changes)
+
+    def pop_all(self):
+        for i in range(len(self.stack)):
+            self.project.history.undo(drop=True)
+
+    def merged(self):
+        result = change.ChangeSet(self.description)
+        for changes in self.stack:
+            for c in self._basic_changes(changes):
+                result.add_change(c)
+        return result
+
+    def _basic_changes(self, changes):
+        if isinstance(changes, change.ChangeSet):
+            for child in changes.changes:
+                for atom in self._basic_changes(child):
+                    yield atom
+        else:
+            yield changes