Reorganize snippets

python/s/difference.md

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+---
+title: List difference
+type: snippet
+language: python
+tags: [list]
+cover: frog-blue-flower
+dateModified: 2020-11-02T19:27:53+02:00
+---
+
+Calculates the difference between two iterables, without filtering duplicate values.
+
+- Create a `set` from `b`.
+- Use a list comprehension on `a` to only keep values not contained in the previously created set, `_b`.
+
+```py
+def difference(a, b):
+  _b = set(b)
+  return [item for item in a if item not in _b]
+```
+
+```py
+difference([1, 2, 3], [1, 2, 4]) # [3]
+```