Fix up ChainMap issue in python-3.5.

volatility/framework/interfaces/layers.py

@@ -7,7 +7,7 @@ import math
 import multiprocessing
 import traceback
 from abc import ABCMeta, abstractmethod
-from typing import Any, Callable, ChainMap, Dict, Iterable, List, Mapping, Optional, Tuple, Union
+from typing import Any, Callable, Dict, Iterable, List, Mapping, Optional, Tuple, Union
 
 from volatility.framework import constants, exceptions, interfaces, validity
 
@@ -93,7 +93,7 @@ class DataLayerInterface(interfaces.configuration.ConfigurableInterface, validit
     It directly accesses a data source and exposes it within volatility."""
 
     _direct_metadata = collections.ChainMap({}, {'architecture': 'Unknown',
-                                                 'os': 'Unknown'})  # type: ChainMap[str, str]
+                                                 'os': 'Unknown'})  # type: collections.ChainMap[str, str]
 
     def __init__(self,
                  context: 'interfaces.context.ContextInterface',