added the String method to Result type

Signed-off-by: André Martins <aanm90@gmail.com>

pkg/types/types.go

@@ -16,6 +16,7 @@ package types
 
 import (
 	"encoding/json"
+	"fmt"
 	"net"
 	"os"
 )
@@ -75,6 +76,20 @@ func (r *Result) Print() error {
 	return prettyPrint(r)
 }
 
+// String returns a formatted string in the form of "[IP4: $1,][ IP6: $2,] DNS: $3" where
+// $1 represents the receiver's IPv4, $2 represents the receiver's IPv6 and $3 the
+// receiver's DNS. If $1 or $2 are nil, they won't be present in the returned string.
+func (r *Result) String() string {
+	var str string
+	if r.IP4 != nil {
+		str = fmt.Sprintf("IP4:%+v, ", *r.IP4)
+	}
+	if r.IP6 != nil {
+		str += fmt.Sprintf("IP6:%+v, ", *r.IP6)
+	}
+	return fmt.Sprintf("%sDNS:%+v", str, r.DNS)
+}
+
 // IPConfig contains values necessary to configure an interface
 type IPConfig struct {
 	IP      net.IPNet