}

switch x := f(); {  // missing switch expression means "true"
case x < 0: return -x
default: return x
}

switch {
case x < y: f1()
case x < z: f2()
case x == 4: f3()
}
</pre>

<p>
Implementation restriction: A compiler may disallow multiple case
expressions evaluating to the same constant.
For instance, the current compilers disallow duplicate integer,