code: function checkZipFile(zipFilePath, cb) {
    //Checking that it is a ZIP file
    mimeInspector.detectFile(zipFilePath, function(err, fileMimetype) {
      var errMessage;
      if (err) {
        logger.error("Error detecting ZIP file", err);
        return cb(err);
      }
  
      if (fileMimetype !== 'application/zip') {
        errMessage = "Expected the file MIME type to be application/zip but was " + fileMimetype;
        logger.error(errMessage);
      }
  
      return cb(errMessage);
    });
  }
docs: checkZipFile - Checking that the file exists and is a zip file.
  
  @param  {string} zipFilePath Path to the zip file.
  @param  {function} cb      description