Add deep symbolizing util for Hash.
user
```ruby
class Hash
  # Destructively convert all keys by using the block operation.
  # This includes the keys from the root hash and from all
  # nested hashes.
  def deep_transform_keys!(&block)
    keys.each do |key|
      value = delete(key)
      self[yield(key)] = value.is_a?(Hash) ? value.deep_transform_keys!(&block) : value
    end
    self
  end

  # Destructively convert all keys to symbols, as long as they respond
  # to +to_sym+. This includes the keys from the root hash and from all
  # nested hashes.
  def deep_symbolize_keys!
    deep_transform_keys!{ |key| key.to_sym rescue key }
  end
end
```
assistant