function transformZipOutput(type, content, mimeType) {
    switch(type) {
        case "blob" :
            return utils.newBlob(utils.transformTo("arraybuffer", content), mimeType);
        case "base64" :
            return base64.encode(content);
        default :
            return utils.transformTo(type, content);
    }
}
Apply the final transformation of the data. If the user wants a Blob for
example, it's easier to work with an U8intArray and finally do the
ArrayBuffer/Blob conversion.
@param {String} type the name of the final type
@param {String|Uint8Array|Buffer} content the content to transform
@param {String} mimeType the mime type of the content, if applicable.
@return {String|Uint8Array|ArrayBuffer|Buffer|Blob} the content in the right format.