def METHOD_NAME(blocksize):
    input_first_vector_collection = np.random.randn(3)
    input_second_vector_collection = np.random.randn(3, blocksize)
    test_vector_collection = _batch_product_i_ik_to_k(
        input_first_vector_collection, input_second_vector_collection
    )
    correct_vector_collection = np.einsum(
        "i,ij->j", input_first_vector_collection, input_second_vector_collection
    )
    assert_allclose(test_vector_collection, correct_vector_collection)