Writing some code to grasp the fundamentals of go.

1. read and write a file
2. serve a http server
3. rest endpoints
4. read and write to a postgres table
5. CORS
6. exporting code
7. importing code from other files
8. interfaces to create functions with flexible types
9. extending interfaces to implement trait bounds
10. concurrency using waitgroups
11. buffered and unbuffered channels
12. deadlocks