code: func (n Network) Covers(o Network) bool {
  	if len(n.Number) != len(o.Number) {
  		return false
  	}
  	nMaskSize, _ := n.IPNet.Mask.Size()
  	oMaskSize, _ := o.IPNet.Mask.Size()
  	return n.Contains(o.Number) && nMaskSize <= oMaskSize
  }
docs: // Contains returns true if Network covers o, false otherwise