"split" is the same as "split /\s+/".

Not quite the same:

no warnings 'uninitialized';
$_ = '  a string with leading whitespace';
print join( ':', split ), "\n";  
print join( ':', split /\s+/ ), "\n";
______
a:string:with:leading:whitespace
:a:string:with:leading:whitespace
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