func (v keyValue) key() interface{} {
	return v.k
}
key implements the nodeContent interface.
package collections
import (
	"fmt"
	"github.com/tideland/golib/errors"
)
type nodeContent interface {
	key() interface{}
	value() interface{}
	deepCopy() nodeContent
}
type justValue struct {
	v interface{}
}
func (v justValue) key() interface{} {
	return v.v
}
func (v justValue) value() interface{} {
	return v.v
}
func (v justValue) deepCopy() nodeContent {
	return justValue{v.v}
}
func (v justValue) String() string {
	return fmt.Sprintf("%v", v.v)
}
type keyValue struct {
	k interface{}
	v interface{}
}