for (keys %hash) {
	print;
}

##</code><code>##

for (key %thisisnotintendedasaseriousquestion) {
	print;
}

##</code><code>##

for (keys %hash) {
	print;
}

for (key %somename) {
	print;
}

##</code><code>##

I see this in a book:

for (keys %hash) {
	print;
}

But it doesn't work in my example, please 
<a href="www.somedomain.com/dev/null>look at it here!</a>