new file: kata solution 'mean square error'

src/kata_mean_square_error.py

@@ -0,0 +1,13 @@
+"""
+Lösung des Katas: Mean Square Error von kylehill
+Link zum Kata: https://www.codewars.com/kata/51edd51599a189fe7f000015
+
+"""
+
+
+def solution(array_a, array_b):
+    numbers_list = list(zip(array_a, array_b))
+    differences = [x[0] - x[1] for x in numbers_list]
+    mean_square_error = sum([x * x for x in differences]) / len(differences)
+
+    return mean_square_error