Not truly these lessions are for best practice's only but it could be your success path to learn go basics to reach the next level of unederstanding in go.
All the lessions are number wise in a hierarchical way so go step by step, they are example of code and what kind of exmaple they are you can get it by folder names. Few code will not work, because they are exmple of some error's and i am using to explain few cases.
Type assertion example: https://play.golang.org/p/QXOs80swGv2