lecture 9 - https://colab.research.google.com/drive/1IIwixgIKSiEC3KQ7z1jwOpVpVwL1GAUl?usp=sharing
lecture 10/11 - https://colab.research.google.com/drive/1EjTlwqh9bni6DpB_oUSMBZEI5kvkZdR7?usp=sharing
lecture 12 - https://colab.research.google.com/drive/1QnfJ38XhalwkzbOT8JpYXf0-IUI1Y8dq?usp=sharing
lecture 13 - https://colab.research.google.com/drive/1i_M6CKz9Q6kKK4wBYD9hljTifz1oHjQ9?usp=sharing
lecture 14 - https://colab.research.google.com/drive/1mU7D_3uqVRtE7Sw2RhS96izs6YUJ3xuw?usp=sharing