chapter6/

Implement these additional methods: func (*IntSet) Len() int // return the number of elements func (*IntSet) Remove(x int) // remove x from the set func (*IntSet) Clear() // remove all elements from the set func (*IntSet) Copy() *IntSet // return a copy of the set

Define a variadic (*IntSet).AddAll(...int) method that allows a list of values to be added, such as s.AddAll(1, 2, 3)

(*IntSet).UnionWith computes the union of two sets unhsing |, the word-parallel bitwise OR operator.

Add a method Elemsx that returns a slice containein the elements of the set, suitable for itrating over with a range loop.

The type of each word used by IntSet is uint64, but 64-bit airthmetic may be ineffictinetn on a 32-bit platform.