@staticmethod
def list(uri='', recursive=False, human_readable=False, summarize=False):
    """
        List files/folders in a bucket if a URI is specified or list available buckets.

        :param uri: S3 bucket URI
        :param recursive: Recursively list files/folders
        :param human_readable: Displays file sizes in human readable format
        :param summarize: Displays summary information (number of objects, total size)
        :return: Command string
        """
    cmd = 'aws s3 ls {uri}'
    cmd += ' --recursive' if recursive else ''
    cmd += ' --human-readable' if human_readable else ''
    cmd += ' --summarize' if summarize else ''
    return cmd.format(uri=uri)
