Because curly brackets (braces) are used for several other things
           including BLOCKs, you may occasionally have to disambiguate braces
           at the beginning of a statement by putting a "+" or a "return" in
           front so that Perl realizes the opening brace isn't starting a
           BLOCK.  The economy and mnemonic value of using curlies is deemed
           worth this occasional extra hassle.

           For example, if you wanted a function to make a new hash and return
           a reference to it, you have these options:

               sub hashem {        { @_ } }   # silently wrong
               sub hashem {       +{ @_ } }   # ok
               sub hashem { return { @_ } }   # ok

           On the other hand, if you want the other meaning, you can do this:

               sub showem {        { @_ } }   # ambiguous (currently ok, but may change)
               sub showem {       {; @_ } }   # ok
               sub showem { { return @_ } }   # ok

           The leading "+{" and "{;" always serve to disambiguate the expres-
           sion to mean either the HASH reference, or the BLOCK.