# File lib/rack/perftools_profiler/profile_data_action.rb, line 11
    def self.check_printer(printer, env=nil)
      if printer != nil && printer != '' && !ProfilerMiddleware::PRINTERS.member?(printer.to_sym)
        message = "Invalid printer type: #{printer}. Valid printer values are #{ProfilerMiddleware::PRINTERS.join(", ")}" 
        raise ProfilerArgumentError, message
      end
    end