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python/snippets/union.md

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+---
+title: List union
+type: snippet
+tags: [list]
+cover: river-houses
+dateModified: 2020-11-02T19:28:35+02:00
+---
+
+Returns every element that exists in any of the two lists once.
+
+- Create a `set` with all values of `a` and `b` and convert to a `list`.
+
+```py
+def union(a, b):
+  return list(set(a + b))
+```
+
+```py
+union([1, 2, 3], [4, 3, 2]) # [1, 2, 3, 4]
+```