MEDIUM
sink((c & MEDIUM) != 0); /* might be useful to warn about */
sink((c | MEDIUM) != 0); /* might be useful to warn about */
c |= MEDIUM; /* might be useful to warn about */
c &= MEDIUM; /* might be useful to warn about */
c &= ~(unsigned)MEDIUM; /* might be useful to warn about */
print_color(MEDIUM);