why do they do `p=new(int)`?

gistfile1.txt

// Go is fully garbage collected. It has pointers but no pointer arithmetic.
// You can make a mistake with a nil pointer, but not by incrementing a pointer.
func learnMemory() (p, q *int) {
    // Named return values p and q have type pointer to int.
    p = new(int) // Built-in function new allocates memory.
    // The allocated int is initialized to 0, p is no longer nil.
    s := make([]int, 20) // Allocate 20 ints as a single block of memory.
    s[3] = 7             // Assign one of them.
    r := -2              // Declare another local variable.
    return &s[3], &r     // & takes the address of an object.
}