对散列进行sort排序，只是会产生一个顺序，但这顺序和初始化时的顺序不一致

    109 my $slice_layouts;
    110 my $vertical_assignment;
    111 my %map_function_indices = (
    112     "OK_func" => "open_statement",
    113     "package_VAR" => "positional",
    114     "split_func" => "prototypes",
    115 );
    116 foreach $slice_layouts ( keys %map_function_indices){
    117     $vertical_assignment = $map_function_indices{$slice_layouts};
    118     print "$slice_layouts => $vertical_assignment ";
    119 }

输出：

OK_func => open_statement
split_func => prototypes
package_VAR => positional