Merge pull request #1058 from nathanielmanistaatgoogle/python-refactoring

src/python/src/grpc/_adapter/_links_test.py

src/python/src/grpc/_adapter/_lonely_rear_link_test.py

src/python/src/grpc/_adapter/fore.py

src/python/src/grpc/_adapter/rear.py

src/python/src/grpc/framework/base/packets/_reception.py

src/python/src/grpc/framework/base/packets/_transmission.py

src/python/src/grpc/framework/base/packets/packets.py