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: environment_walker.rb
    path of file: ./repos/rbs/lib/rbs
    
    the code of the file until where you have to start completion: # frozen_string_literal: true

module RBS
  class EnvironmentWalker
    InstanceNode = _ = Struct.new(:type_name, keyword_init: tru
    
    def tsort_each_node(&block)
      env.class_decls.each_key do |type_name|
        yield InstanceNode.new(type_name: type_name)
        yield SingletonNode.new(type_name: type_name)
      end
      env.interface_decls.each_key do |type_name|
        yield TypeNameNode.new(type_name: type_name)
      end
      env.type_alias_decls.each_key do |type_name|
        yield TypeNameNode.new(type_name: type_name)
      end
    end