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: trace_output.rb
    path of file: ./repos/rake/lib/rake
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
module Rake
  module TraceOutput # :nodoc: all

 
    
    def trace_on(out, *strings)
      sep = $\ || "\n"
      if strings.empty?
        output = sep
      else
        output = strings.map { |s|
          next if s.nil?
          s.end_with?(sep) ? s : s + sep
        }.join
      end