Add distributed computing for negation and addition (no memory distributing)

test/test_matrix.py

@@ -378,3 +378,12 @@ class TestMatrix(TestCase):
         expected = Matrix([1, 2, 3, 4, 5, 60, 70, 8, 9, 100, 110, 12, 13, 14, 15, 16], (4, 4))
 
         self.assertEqual(expected, actual)
+
+    def test_should_flatten_list_of_matrices(self):
+        m1 = Matrix([1, 2, 3, 4, 5, 6, 7, 8, 9], (3, 3))
+        m2 = Matrix([1, 2, 3, 4, 5, 6], (2, 3))
+
+        actual = m1.flatten([m1, m2])
+        expected = Matrix([1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4, 5, 6], (5, 3))
+
+        self.assertEqual(expected, actual)