in Python: Return the sum of the products of the corresponding items of the lists vector1, vector2, and vector3 if they have the same length. If not, then return None.  :param vector1: list of numbers :param vector2: list of numbers :param vector3: list of numbers :return: number or None  >>> vector_product([1,2,3], [4,5,6], [-3, -2, -1]) -50 >>> vector_product([2],[-3.5], [-3]) 21.0 >>> vector_product([1,2], [5, 6, 7], [0, 1.5])