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: to_bs.rb
    path of file: ./repos/rdoc/lib/rdoc/markup
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
##
# Outputs RDoc markup with hot backspace action!  You will pro
    
  def convert_string string
    return string unless @in_b or @in_em
    chars = if @in_b then
              string.chars.map do |char| "#{char}\b#{char}" end
            elsif @in_em then
              string.chars.map do |char| "_\b#{char}" end
            end

    chars.join
  end

end