New will return a Record based on the input time.Time `t`, level.Level `lv`, message string `msg` and attributes `attrs`.

Record interface describes the behavior that a Record should have It expose getter methods for its elements, as well as two helper methods: - `AddAttr()` will return a copy of this Record with the input Attr appended to the existing ones - `AttrLen()` will return the length of the attributes in the record.