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+#!/usr/bin/python3
+# https://theweeklychallenge.org/blog/perl-weekly-challenge-242/#TASK1
+#
+# Task 1: Missing Members
+# =======================
+#
+# You are given two arrays of integers.
+#
+# Write a script to find out the missing members in each other arrays.
+#
+## Example 1
+##
+## Input: @arr1 = (1, 2, 3)
+##        @arr2 = (2, 4, 6)
+## Output: ([1, 3], [4, 6])
+##
+## (1, 2, 3) has 2 members (1, 3) missing in the array (2, 4, 6).
+## (2, 4, 6) has 2 members (4, 6) missing in the array (1, 2, 3).
+#
+## Example 2
+##
+## Input: @arr1 = (1, 2, 3, 3)
+##        @arr2 = (1, 1, 2, 2)
+## Output: ([3])
+##
+## (1, 2, 3, 3) has 2 members (3, 3) missing in the array (1, 1, 2, 2). Since they are same, keep just one.
+## (1, 1, 2, 2) has 0 member missing in the array (1, 2, 3, 3).
+#
+############################################################
+##
+## discussion
+##
+############################################################
+#
+# For each element of each array, if it is not in the other array,
+# save it for the output.
+# Example 2 has a caveat though, by not returning an empty array in
+# case of no missing elements it is unclear in which of the arrays
+# the element was originally. It's better to return an empty array
+# here, so let's just do that instead.
+
+def missing_members(arr1: list, arr2: list):
+    seen: dict = {}
+    res1: list = []
+    res2: list = []
+    print("Input: ([", ", ".join(str(x) for x in arr1), "], [", ", ".join(str(x) for x in arr2), "])")
+    for elem in arr1:
+        if elem in seen:
+            next
+        else:
+            if elem not in arr2:
+                seen[elem] = 1
+                res1.append(elem)
+    seen = {}
+    for elem in arr2:
+        if elem in seen:
+            next
+        else:
+            if elem not in arr1:
+                seen[elem] = 1
+                res2.append(elem)
+    print("Output: ([", ", ".join(str(x) for x in res1), "], [", ", ".join(str(x) for x in res2), "])")
+
+missing_members( [ 1, 2, 3 ], [ 2, 4, 6 ] );
+missing_members( [ 1, 2, 3, 3 ], [ 1, 1, 2, 2 ] );
+