code: func (caaSet CAASet) criticalUnknown() bool {
  	if len(caaSet.Unknown) > 0 {
  		for _, caaRecord := range caaSet.Unknown {
  			// The critical flag is the bit with significance 128. However, many CAA
  			// record users have misinterpreted the RFC and concluded that the bit
  			// with significance 1 is the critical bit. This is sufficiently
  			// widespread that that bit must reasonably be considered an alias for
  			// the critical bit. The remaining bits are 0/ignore as proscribed by the
  			// RFC.
  			if (caaRecord.Flag & (128 | 1)) != 0 {
  				return true
  			}
  		}
  	}
  
  	return false
  }
docs: // returns true if any CAA records have unknown tag properties and are flagged critical.