Iterating over hash keys

[nowox]

Let's consider the hash my %hash = ( foo => { a => 42, b => 43, c => 44 } );

It would be interesting to implement something that allows to iterate over hash keys

{{#hash.keys}}
    {{.}}
{{/hash}}

In case of more complex data we can still imaging using the same kind of syntax:

{{#hash.keys}}
    {{.}} {{name}} {{genre}}
{{/hash.keys}}

Or even a full nested hash support:

{{#animals.keys}}
    {{.}}:
    {{#mammal.keys}} 
        {{.}} -> {{name}}
    {{/mammal.keys
{{/hash.keys}}

What do you think?