code: func (p *intPool) getZero() *big.Int {
  	if p.pool.len() > 0 {
  		return p.pool.pop().SetUint64(0)
  	}
  	return new(big.Int)
  }
docs: // getZero retrieves a big int from the pool, setting it to zero or allocating
  // a new one if the pool is empty.