Add return value for recur function of Python in space complexity (#1169)

* Add return value for recur function of Python in space complexity

* Update space_complexity.md

* Update space_complexity.md

---------

Co-authored-by: Yudong Jin <krahets@163.com>

docs-en/chapter_computational_complexity/space_complexity.md

@@ -476,9 +476,10 @@ Consider the following code, the term "worst-case" in worst-case space complexit
         for _ in range(n):
             function()
 
-    def recur(n: int) -> int:
+    def recur(n: int):
         """Recursion O(n)"""""
-        if n == 1: return
+        if n == 1:
+            return
         return recur(n - 1)
     ```
 

docs/chapter_computational_complexity/space_complexity.md

@@ -475,9 +475,10 @@
         for _ in range(n):
             function()
 
-    def recur(n: int) -> int:
+    def recur(n: int):
         """递归的空间复杂度为 O(n)"""
-        if n == 1: return
+        if n == 1:
+            return
         return recur(n - 1)
     ```