implement add, subtract, multiply of vectors

vector.py

@@ -18,3 +18,19 @@ def __str__(self):
 
     def __eq__(self, v):
         return self.coordinates == v.coordinates
+
+    def __ne__(self, v):
+        return self.coordinates != v.coordinates
+
+    def __add__(self, v):
+        new_coordinates = [x+y for x,y in zip(self.coordinates, v.coordinates)] 
+        return Vector(new_coordinates)
+
+    def __sub__(self, v):
+        new_coordinates = [x-y for x,y in zip(self.coordinates, v.coordinates)]
+        return Vector(new_coordinates)
+
+    def __mul__(self, v):
+        new_coordinates = [x*y for x,y in zip(self.coordinates, v.coordinates)]
+        return Vector(new_coordinates)
+