trie.go
func (p *prefixTrie) CoveredNetworks(network net.IPNet) ([]RangerEntry, error) {
	net := rnet.NewNetwork(network)
	return p.coveredNetworks(net)
}
func (p *prefixTrie) CoveredNetworks(network net.IPNet) ([]RangerEntry, error) {
	net := rnet.NewNetwork(network)
	return p.coveredNetworks(net)
}
// CoveredNetworks returns the list of RangerEntry(s) the given ipnet
// covers.  That is, the networks that are completely subsumed by the
// specified network.