7.1_1 Progressive Waves: https://docs.google.com/document/d/1fxgia0Gue9VzB9SG9gtZ18srzOpQ64rehwdboeqDn7g/edit?usp=sharing
7.1_2 Progressive Waves: https://docs.google.com/document/d/1r2daVU9DRkjsKGYoYhC6Yku6O7RwcWAHjEVvB0HfzMk/edit?usp=sharing
7.1_3 Progressive Waves:
https://docs.google.com/document/d/1ui24JpHeL3pkZkiN75lihG0VnYdgenyVqiENwXcKNQM/edit?usp=sharing
Medium Progessive Waves Medium
https://docs.google.com/document/d/1KoROz5QGrKLPGelyYfkrnIcwsk1Dq_t8V9gTZEuwU-E/edit?usp=sharing
Medium Progessive Waves hard
https://docs.google.com/document/d/1VSd9vdqO2FH8kmzw5HZZUvlPe85dWAaAhjiQwyL8x1M/edit?usp=sharing