my %foo;
@foo{qw/ foo bar baz /} = 1 .. 3;
printf "%%foo = %s { %s } = ( %s )\n",\%foo,scalar %foo,
       join(",",map "$_ => $foo{$_}",keys %foo);
while (%foo) {
    my $key = each %foo;
    my $val = delete $foo{$key};
    printf "%s => %s is gone.\n", $key, $val;
    printf "%%foo = %s { %s } = ( %s )\n",\%foo,scalar %foo,
           join(",",map "$_ => $foo{$_}",keys %foo);
}