type multiCore … var _ … var _ … // NewTee creates a Core that duplicates log entries into two or more // underlying Cores. // // Calling it with a single Core returns the input unchanged, and calling // it with no input returns a no-op Core. func NewTee(cores ...Core) Core { … } func (mc multiCore) With(fields []Field) Core { … } func (mc multiCore) Level() Level { … } func (mc multiCore) Enabled(lvl Level) bool { … } func (mc multiCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry { … } func (mc multiCore) Write(ent Entry, fields []Field) error { … } func (mc multiCore) Sync() error { … }