def _is_gse2(filename):
    """
    Checks whether a file is GSE2.0 format.

    :type filename: str
    :param filename: Name of the GSE2.0 file to be checked.
    :rtype: bool
    :return: ``True`` if GSE2.0 file.
    """
    try:
        with open(filename, 'rb') as fh:
            temp = fh.read(12)
    except Exception:
        return False
    if temp != b'BEGIN GSE2.0':
        return False
    return True