$foo = 'foo';
sub printfoo { print $foo; }
printfoo();             # prints 'foo'
{ local $foo = 'bar';
  printfoo();           # prints 'bar'
}
printfoo();             # prints 'foo'

##</code><code>##

$foo = 'foo';
sub printfoo { print $foo; }
printfoo();                 #prints 'foo'
{ my $hidden_foo = $foo;
  $foo = 'bar';
  &printfoo();              #prints 'bar'
  $foo = $hidden_foo;
}
printfoo()                  #prints 'foo'