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: test_lexer.rb
    path of file: ./repos/ruby-packer/ruby/test/ripper
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
begin
  require 'ripper'
  require 'test/unit'
  module TestRipper; end
re
    
  def test_nested_dedent_heredoc
    bug = '[ruby-core:80977] [Bug #13536]'
    str = <<~'E'
    <<~"D"
    #{
    <<~"B"
    this must be a valid ruby
    B
    }
    D
    E
    assert_equal(str, Ripper.tokenize(str).join(""), bug)

    str = <<~'E'
    <<~"D"
    #{
    <<~"B"
      this must be a valid ruby
    B
    }
    D
    E
    assert_equal(str, Ripper.tokenize(str).join(""), bug)
  end