Wrong type winston.LogMethod for messageFormatter

[afharo]

Hi as of now, winston.LogMethod is defined as https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/winston/index.d.ts#L490

But messageFormatter should be a function that receives 1 parameter logObject with {level: string, msg: string, meta: any} and returns a string.

winston-cloudwatch/typescript/winston-cloudwatch.d.ts

Line 24 in e3a0927

messageFormatter?: winston.LogMethod;