def METHOD_NAME(file_uri: str) -> str:
    if not os.path.isfile(file_uri):
        raise NotReadableError(f'Could not read {file_uri}')
    file_size = os.path.getsize(file_uri)
    with open(file_uri, 'r') as in_file, io.StringIO() as str_buffer:
        with progressbar(
                in_file, 'read', file_size, desc='Reading file') as bar:
            shutil.copyfileobj(bar, str_buffer)
        return str_buffer.getvalue()