# File lib/openurl/transport.rb, line 38
                def add_context_object(contextobject)
      
      if contextobject.is_a?(OpenURL::ContextObject)
        @context_objects << contextobject
      elsif contextobject.is_a?(Array)
        contextobject.each do | co |
          raise ArgumentError, "Each element in array much be an OpenURL::ContextObject!" unless co.is_a?(OpenURL::ContextObject)          
          @context_objects << co
        end      
      else 
        raise ArgumentError, "Argument must be a ContextObject or array of ContextObjects!, #{contextobject.class} sent."        
      end       
                end