def upload_files(self, file_list):
        """ upload_files: uploads files to server
            Args:
                file_list (str): list of files to upload
            Returns: None
        """
        counter = 0
        files_to_upload = list(set(file_list) - set(self.uploaded_files)) # In case restoring from previous session
        try:
            for f in files_to_upload:
                with open(config.get_storage_path(f), 'rb') as file_obj:
                    response = config.SESSION.post(config.file_upload_url(), files={'file': file_obj})
                    if response.status_code == 200:
                        response.raise_for_status()
                        self.uploaded_files.append(f)
                        counter += 1
                        config.LOGGER.info("\tUploaded {0} ({count}/{total}) ".format(f, count=counter, total=len(files_to_upload)))
                    else:
                        self.failed_uploads[f] = response._content.decode('utf-8')
        finally:
            config.PROGRESS_MANAGER.set_uploading(self.uploaded_files)
upload_files: uploads files to server
            Args:
                file_list (str): list of files to upload
            Returns: None