Ex. Slice is in the middle of an array, what will happen in that array after append?
=> Array value will reflect slice change, but array instance will change after appended slice capacity larger than array
Ex, Use built-in function copy to copy elements from one slice to another
Copy won't work if length is not enough
Copied slice refer to the same array? What will happen when we modify value from copied slice?
=> Modification in copied slice won't affect original array.
Must not assume modification in old slice will affect new slice
Ex. Declare function with ... makes function variadic, can accept any numbers of arguments.
Ex. Remove the middle of a slice.
It seems underlying array won't be removed when we just remove from slice, need to be careful of this part.
Easy to confuse.
