func (l *Logger) Error(msg string) {
	NewEntry(l).Error(msg)
}
Error level message.
package log
import stdlog "log"
var _ Interface = (*Logger)(nil)
type Fielder interface {
	Fields() Fields
}
type Fields map[string]interface{}
func (f Fields) Fields() Fields {
	return f
}
type HandlerFunc func(*Entry) error
func (f HandlerFunc) HandleLog(e *Entry) error {
	return f(e)
}
type Handler interface {
	HandleLog(*Entry) error
}
type Logger struct {
	Handler Handler
	Level   Level
}
func (l *Logger) WithFields(fields Fielder) *Entry {
	return NewEntry(l).WithFields(fields.Fields())
}
func (l *Logger) WithField(key string, value interface{}) *Entry {
	return NewEntry(l).WithField(key, value)
}
func (l *Logger) WithError(err error) *Entry {
	return NewEntry(l).WithError(err)
}
func (l *Logger) Debug(msg string) {
	NewEntry(l).Debug(msg)
}
func (l *Logger) Info(msg string) {
	NewEntry(l).Info(msg)
}
func (l *Logger) Warn(msg string) {
	NewEntry(l).Warn(msg)
}