class Hash
  def reverse_merge(other_hash)
    other_hash.merge(self)
  end
  def reverse_merge!(other_hash)
    replace(reverse_merge(other_hash))
  end
  def deep_transform_keys(&block)
    result = {}
    each do |key, value|
      result[yield(key)] = value.is_a?(Hash) ? value.deep_transform_keys(&block) : value
    end
    result
  end

  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
end