func (b *OpenBitSet) IsEmpty() bool {
	return b.Cardinality() == 0
}
/* Returns true if there are no set bits
package util
import (
	"bytes"
	"fmt"
)
type OpenBitSet struct {
	bits    []int64
	wlen    int    
	numBits int64  
}
func NewOpenBitSetOf(numBits int64) *OpenBitSet {
	assert(numBits > 0)
	bits := make([]int64, bits2words(numBits))
	return &OpenBitSet{
		numBits: numBits,
		bits:    bits,
		wlen:    len(bits),
	}
}
func NewOpenBitSet() *OpenBitSet {
	return NewOpenBitSetOf(64)
}