Merge pull request #23 from deepserket/master

Fix some issues

snippets/compact.md

@@ -6,9 +6,9 @@ Use `filter()` to filter out falsey values (False, None, 0, and "").
 
 ```python
 def compact(arr):
-    return list(filter(lambda x: bool(x), arr))
+    return list(filter(bool, arr))
 ```
 
 ``` python
 compact([0, 1, False, 2, '', 3, 'a', 's', 34]) # [ 1, 2, 3, 'a', 's', 34 ]
-```
+```

snippets/difference.md

@@ -1,14 +1,13 @@
 ### difference
 
-Returns the difference between two arrays.
+Returns the difference between two iterables.
 
-Create a `set` from `b`, then use list comprehension to only keep values not contained in `b`
+Use list comprehension to only keep values not contained in `b`
 
 ```python
 def difference(a, b):
-    b = set(b)
-    return [item for item in a if item not in b]
+    return [item for item in a if item not in b]
 ```
 ``` python
 difference([1, 2, 3], [1, 2, 4]) # [3]
-```
+```