Add find_key

snippets/find_key.md

@@ -0,0 +1,22 @@
+---
+title: find_key
+tags: dictionary,intermediate
+---
+
+Returns the first key in the provided dictionary that has the given value.
+
+Use `dictionary.items()` and `next()` to return the first key that has a value equal to `val`.
+
+```py
+def find_key(dict, val):
+  return next(key for key, value in dict.items() if value == val)
+```
+
+```py
+ages = {
+  "Peter": 10,
+  "Isabel": 11,
+  "Anna": 9,
+}
+find_key(ages, 11) # "Isabel"
+```