flex 3a syntex

1flex: none                                            /* value 'none' case */
2flex: <'flex-grow'>                                   /* One value syntax, variation 1 */
3flex: <'flex-basis'>                                  /* One value syntax, variation 2 */
4flex: <'flex-grow'> <'flex-basis'>                    /* Two values syntax, variation 1 */
5flex: <'flex-grow'> <'flex-shrink'>                   /* Two values syntax, variation 2 */
6flex: <'flex-grow'> <'flex-shrink'> <'flex-basis'>    /* Three values syntax */
7flex: inherit