Heisenberg questions

• groupby and add some rows
• Select group based on a value in another column
• Slicing string character correctly in C++
• What is the --watch and --debug option in nest start
• How to deal with Exec format error in docker-compose
• How to detect returned class in typescript
• How to generate and set `JWT_SECRET` and `JWT_EXPIRATION_TIME` in express
• How to set not null constraint to columns in postgres
• How to use npm workspace
• How to display specific digit in pandas dataframe

Heisenberg answers