To avoid confusion, in gui code you will often see the &somesub syntax, because often gui's will automatically pass the calling widget as it's first argument to the sub, and the & supresses it. Like:

-command=>[\&raiseit,$win]) 
# passes $win as first arg 
# instead of widget or event
 # not a 100% foolproof rule
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So, even though the somesub() syntax is preferred ( and most correct), be prepared to see other weird constructs. Everytime I write a sub, I usually put

sub somesub{
     print "@_\n";
....
....
}
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as it's first line, just to be sure what I'm getting. Sometimes I surprised by what comes in.