Update word_occurrence.py

Author: Rohanrbharadwaj

strings/word_occurrence.py

@@ -1,6 +1,7 @@
 # Created by sarathkaul on 17/11/19
 # Modified by Arkadip Bhattacharya(@darkmatter18) on 20/04/2020
 from collections import defaultdict
+from typing import DefaultDict
 
 
 def word_occurence(sentence: str) -> dict:
@@ -14,7 +15,7 @@ def word_occurence(sentence: str) -> dict:
     >>> dict(word_occurence("Two  spaces"))
     {'Two': 1, 'spaces': 1}
     """
-    occurrence: dict = defaultdict(int)
+    occurrence: DefaultDict[str, int] = defaultdict(int)
     # Creating a dictionary containing count of each word
     for word in sentence.split():
         occurrence[word] += 1