Struct

1. Struct and type
2. Struct with partial information (default values)
3. Slice of structs
4. Anonymous struct
5. Struct in a struct
6. composition via embedding instead of inheritance
7. Tags and introspection (reflect)
8. use cleanenv
9. methods
10. method of int
11. map keys method
12. method gets copy of struct
13. method pass pointer of struct
14. Exercise: read-csv-struct
15. Exercise: implement 2D point and move
16. Exercise: implement 3D point and move
17. Exercise: implement wc
18. Solution: implement wc