def destos_to_binfmt(key):
    """
	Returns the binary format based on the unversioned platform name,
	and defaults to ``elf`` if nothing is found.

	:param key: platform name
	:type  key: string
	:return: string representing the binary format
	"""
    if key == 'darwin':
        return 'mac-o'
    elif key in ('win32', 'cygwin', 'uwin', 'msys'):
        return 'pe'
    return 'elf'
