Question: I want to transform nested hashes into multidimensional arrays recursivley.

This is my current code:

```
def deep_to_a(hash)
  return  hash.to_a.each {|k, v|
    if k.is_a?(Hash) then
      hash[k.to_a] = hash.delete(k)
      deep_to_a(k)
    elsif v.is_a?(Hash) then
      hash[k] = hash[k].to_a
      if hash[k].any?{|k, v| k.is_a?(Hash) || v.is_a?(Hash)}
        deep_to_a(v)
      end
    end
  }
end

```

I want to get:

```
h = {11=>{12=>13, 14=>15}, 16=>17}
p deep_to_a(h) # => [[11, [[12, 13], [14, 15]]], [16, 17]] 

```

But I get

```
[[11, {12=>13, 14=>15}], [16, 17]]

```

How can I make it work?

Answer: 
A destructive function is hard to debug.
In this case, `map` is better than `each` + destructive assignment.

The result of `hash.to_a` is an array, so your iteration `|k, v|` is incorrect.

```
def deep_to_a(hash)
  hash.map do |v|
    if v.is_a?(Hash) or v.is_a?(Array) then
      deep_to_a(v)
    else
      v
    end
  end
end

h = {11=>{12=>13, 14=>15}, 16=>17}
p deep_to_a(h)
# [[11, [[12, 13], [14, 15]]], [16, 17]]

```
```
def deep_to_a(h)
  h.map { |k,v| [k, Hash === v ? deep_to_a(v) : v] }
end

deep_to_a({11=>{12=>13, 14=>15}, 16=>17})
  #=> [[11, [[12, 13], [14, 15]]], [16, 17]]

```