bitset extendSetMaybe

bitset.go

// len(nil) == 0, and see no value in using cap, when explicitly tracking the length. 
// Has some minor rammifications for other methods reliant on len(b.set) instead of b.length.

func (b *BitSet) extendSetMaybe(i uint) {
	if i >= b.length { // if we need more bits, make 'em
		nsize := (i + wordSize) / wordSize
		if uint(len(b.set)) < nsize {
			newset := make([]uint64, 2*nsize) // increase capacity 2x
			copy(newset, b.set)
			b.set = newset
		}
		b.length = i + 1
	}
}