Add Type Hints in Deterministic Cache

axelrod/deterministic_cache.py

@@ -1,5 +1,6 @@
 from collections import UserDict
 import pickle
+from typing import Tuple
 
 from axelrod import Player
 
@@ -29,7 +30,7 @@ class DeterministicCache(UserDict):
     methods to save/load the cache to/from a file.
     """
 
-    def __init__(self, file_name=None):
+    def __init__(self, file_name: str=None):
         """
         Parameters
         ----------
@@ -42,7 +43,7 @@ def __init__(self, file_name=None):
             self.load(file_name)
 
     @staticmethod
-    def _key_transform(key):
+    def _key_transform(key: Tuple[str, str, int]):
         """
         Parameters
         ----------
@@ -78,7 +79,7 @@ def __setitem__(self, key, value):
         super().__setitem__(self._key_transform(key), value)
 
     @staticmethod
-    def _is_valid_key(key):
+    def _is_valid_key(key) -> boolean:
         """Validate a proposed dictionary key.
 
         Parameters
@@ -116,7 +117,7 @@ def _is_valid_key(key):
         return True
 
     @staticmethod
-    def _is_valid_value(value):
+    def _is_valid_value(value) -> boolean:
         """Validate a proposed dictionary value.
 
         Parameters
@@ -133,7 +134,7 @@ def _is_valid_value(value):
 
         return True
 
-    def save(self, file_name):
+    def save(self, file_name: str):
         """Serialise the cache dictionary to a file.
 
         Parameters
@@ -145,7 +146,7 @@ def save(self, file_name):
             pickle.dump(self.data, io)
         return True
 
-    def load(self, file_name):
+    def load(self, file_name: str) -> boolean:
         """Load a previously saved cache into the dictionary.
 
         Parameters