def get_content_of_file(self, project, repository, filename, at=None, markup=None):
        """
        Retrieve the raw content for a file path at a specified revision.
        The authenticated user must have REPO_READ permission for the specified repository to call this resource.
        :param project:
        :param repository:
        :param filename:
        :param at: OPTIONAL ref string
        :param markup: 	if present or "true", triggers the raw content to be markup-rendered and returned as HTML;
                        otherwise, if not specified, or any value other than "true",
                        the content is streamed without markup
        :return:
        """
        headers = self.form_token_headers
        url = 'projects/{project}/repos/{repository}/raw/{filename}/'.format(project=project,
                                                                             repository=repository,
                                                                             filename=filename)
        params = {}
        if at is not None:
            params['at'] = at
        if markup is not None:
            params['markup'] = markup
        return self.get(url, params=params, not_json_response=True, headers=headers)