You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: mixin_synced_folders.rb
    path of file: ./repos/vagrant/lib/vagrant/action/builtin
    
    the code of the file until where you have to start completion: # Copyright (c) HashiCorp, Inc.
# SPDX-License-Identifier: BUSL-1.1

require "json"
require "set"

require 'vagrant/util/scoped_hash_override'

module Vagrant
  module Action

    
        def synced_folders_diff(one, two)
          existing_ids = {}
          one.each do |impl, fs|
            fs.each do |id, data|
              existing_ids[id] = data
            end
          end

          result = Hash.new { |h, k| h[k] = Set.new }
          two.each do |impl, fs|
            fs.each do |id, data|
              existing = existing_ids.delete(id)
              if !existing
                result[:added] << id
                next
              end

              # Exists, so we have to compare the host and guestpath, which
              # is most important...
              if existing[:hostpath] != data[:hostpath] ||
                existing[:guestpath] != data[:guestpath]
                result[:modified] << id
              end
            end