pickle_idea.py: Make funciton unfamiliar() more robust

app/pickle_idea.py

@@ -6,6 +6,7 @@
 # Purpose: dictionary & pickle as a simple means of database.
 # Task: incorporate the functions into wordfreqCMD.py such that it will also show cumulative frequency.
 
+import os
 import pickle
 from datetime import datetime
 
@@ -55,10 +56,12 @@ def save_frequency_to_pickle(d, pickle_fname):
     f.close()
 
 def unfamiliar(path,word):
-    f = open(path,"rb")
+    if not os.path.exists(path):
+        return None
+    with open(path,"rb") as f:
         dic = pickle.load(f)
         dic[word] += [datetime.now().strftime('%Y%m%d%H%M')]
-    fp = open(path,"wb")
+    with open(path,"wb") as fp:
         pickle.dump(dic,fp)
 
 def familiar(path,word):