Add find_index_of_all

snippets/find_index_of_all.md

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+---
+title: find_index_of_all
+tags: list,intermediate
+---
+
+Returns the indexes of all elements in the provided list that satisfy the provided testing function.
+
+- Use `enumerate()` and a list comprehension to return the indexes of the all element in `lst` for which `fn` returns `True`.
+
+```py
+def find_index_of_all(lst, fn):
+  return [i for i, x in enumerate(lst) if fn(x)]
+```
+
+```py
+find_index_of_all([1, 2, 3, 4], lambda n: n % 2 == 1) # [0, 2]
+```