bpo-36888: Add multiprocessing.parent_process() (GH-13247)

diff --git a/Lib/multiprocessing/context.py b/Lib/multiprocessing/context.py
index 871746b..5a48657 100644
--- a/Lib/multiprocessing/context.py
+++ b/Lib/multiprocessing/context.py
@@ -35,6 +35,7 @@
     AuthenticationError = AuthenticationError
 
     current_process = staticmethod(process.current_process)
+    parent_process = staticmethod(process.parent_process)
     active_children = staticmethod(process.active_children)
 
     def cpu_count(self):