Explain what the append function does in the context of data structures.

In Go, the append function is used to add elements to a slice. It takes a slice and one or more elements to add, and returns a new slice with the added elements.

Example:

numbers := []int{1, 2, 3}
numbers = append(numbers, 4, 5)
// Now numbers contains [1 2 3 4 5]

If there is not enough space in the slice for new elements, append automatically allocates a new array and copies the data there, so it is important to assign the result back to the slice variable.

append is a convenient way to dynamically extend slices without manual memory management.