code: func (d *DeliverClient) GetSpecifiedBlock(num uint64) (*cb.Block, error) {
  	err := d.seekSpecified(num)
  	if err != nil {
  		return nil, errors.WithMessage(err, "error getting specified block")
  	}
  
  	return d.readBlock()
  }
docs: // GetSpecifiedBlock gets the specified block from a peer/orderer's deliver
  // service