    # File lib/chef/role.rb, line 132
        def env_run_lists(env_run_lists=nil)
          if (!env_run_lists.nil?)
            unless env_run_lists.key?("_default")
              msg = "_default key is required in env_run_lists.\n"
              msg << "(env_run_lists: #{env_run_lists.inspect})"
              raise Chef::Exceptions::InvalidEnvironmentRunListSpecification, msg
            end
            @env_run_lists.clear
            env_run_lists.each { |k,v| @env_run_lists[k] = Chef::RunList.new(*Array(v))}
          end
          @env_run_lists
        end