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: staleness_checker.rb
    path of file: ./repos/stackneveroverflow/vendor/bundle/ruby/2.3.0/gems/sass-3.4.24/lib/sass/plugin
    
    the code of the file until where you have to start completion: require 'thread'

module Sass
  module Plugin
    # The class handles `.s[ca]ss` file staleness checks via their mtime timestamps.
    #
    # To speed things up two level of caches are employed:
    #
    # * A class-level dependency cache which stores @import pat
    
      def dependencies_stale?(uri, importer, css_mtime)
        timestamps = @dependencies_stale[[uri, importer]] ||= {}
        timestamps.each_pair do |checked_css_mtime, is_stale|
          if checked_css_mtime <= css_mtime && !is_stale
            return false
          elsif checked_css_mtime > css_mtime && is_stale
            return true
          end
        end