Zero value of a slice is nil.
A nil slice has length and capacity of 0.
A nil slice has no underlying array.
A non-nil slice can also have length and capacity of 0, like []int{} or make([]int, 5)[5:].
Any type that has nil values can be converted to nil slice:
https://codeeval.dev/gist/d36abe37a7da46e28a2374a549a1f6cd
To test whether a slice is empty, check if len(s) is 0: