code: func (b *Bitset) At(index int) bool {
  	if index >= b.numBits {
  		log.Panicf("Index %d out of range", index)
  	}
  
  	return (b.bits[index/8] & (0x80 >> byte(index%8))) != 0
  }
docs: // At returns the value of the bit at |index|.