# File lib/hashie/mash.rb, line 151
    def deep_update(other_hash, &blk)
      other_hash.each_pair do |k, v|
        key = convert_key(k)
        if regular_reader(key).is_a?(Mash) && v.is_a?(::Hash)
          custom_reader(key).deep_update(v, &blk)
        else
          value = convert_value(v, true)
          value = convert_value(blk.call(key, self[k], value), true) if blk
          custom_writer(key, value, false)
        end
      end
      self
    end