Adopted new convention from template

src/Python/Problems001-050/Problem021.py

@@ -32,12 +32,13 @@ def compute():
     """
 
     n = 10_000
-    sum_amicable = 0
+    ans = 0
     for i in range(1, n):
         value = sum_divisors(i)
         if i != value and sum_divisors(value) == i:
-            sum_amicable += i
+            ans += i
-    return sum_amicable
+
+    return ans
 
 
 if __name__ == "__main__":