function() {
        return {
            token: this.token,
            payload: this.payload,
            valid: this.valid,
            expired: this.expired,
            stale: this.stale
        };
    }
function() {
        return {
            token: this.token,
            payload: this.payload,
            valid: this.valid,
            expired: this.expired,
            stale: this.stale
        };
    }
function ( ) { return { token : this . token , payload : this . payload , valid : this . valid , expired : this . expired , stale : this . stale } ; }
toJSON - this function is called when the jwt is passed through JSON.stringify
we don't want the secret or options to be stringified
@return object
toJSON - this function is called when the jwt is passed through JSON . stringify we don t want the secret or options to be stringified