FOSSA

snippets/count_by.md

@@ -1,5 +1,7 @@
 ### count_by
 
+:information_source: Already implemented via `collections.Counter`
+
 Groups the elements of a list based on the given function and returns the count of elements in each group.
 
 Use `map()` to map the values of the list using the given function. Iterate over the map and increase the the elements count each time it occurs.

snippets/difference_by.md

@@ -0,0 +1,11 @@
+### difference_by
+``` python
+def difference_by(a, b, fn):
+    b = set(map(fn,b))
+    return [item for item in a if fn(item) not in b]
+```
+
+```python
+difference_by([2.1, 1.2], [2.3, 3.4],floor); // [1.2]
+difference_by([{ 'x': 2 }, { 'x': 1 }], [{ 'x': 1 }], lambda v : v['x']); // [ { x: 2 } ]
+```

snippets/spread.md

@@ -1,6 +1,6 @@
 ### spread
 
-Implements javascript's spread syntax as a function. Flattens the list(non-deep) and returns an list.
+Implements javascript's `[].concat(...arr)`. Flattens the list(non-deep) and returns an list.
 
 ```python
 def spread(arg):