not on book Chapter Play Well

Can someone explain this?

if ENV['NO_RUN']
  def system(cmd)
    puts cmd
    true
  end
end
if false
system(command)
end

It’s not explained in the book. Lots of sections in the downloaded files differ greatly from the book, like the <<-EOS heredoc

I wouldn’t dig too deeply into the code that isn’t pulled into the book – this is here to allow me to test some of the code without actually running <a href="mailto:mysqldump”>mysqldump@. Testing techniques like this will be covered in chapter 8 and will involve more readable code, I promise :)