Update u2/list_ops.py

u2/list_ops.py

@@ -1,14 +1,14 @@
 def length(l):
     count = 0
-    for c in range l:
+    for item in range l:
         count +=1
     return count
 
 def append(list1, list2):
-    list = []
+    result = []
     for item in list1:
-        list += [item]
+        result += [item]
     for item in list2:
-        list += [item]
-    return list
+        result += [item]
+    return result