class Hashie::Mash

def _deep_update(other_hash, &blk)
  other_hash.each_pair do |k, v|
    key = convert_key(k)
    if v.is_a?(::Hash) && key?(key) && regular_reader(key).is_a?(Mash)
      custom_reader(key).deep_update(v, &blk)
    else
      value = convert_value(v, true)
      value = convert_value(yield(key, self[k], value), true) if blk && key?(k)
      custom_writer(key, value, false)
    end
  end
end