# File lib/ruote/util/dollar.rb, line 152
    def call_ruby (ruby_code)

      return '' if @fexp.context['ruby_eval_allowed'] != true

      engine_id = @fexp.context.engine_id

      wi = Ruote::Workitem.new(@workitem)
      workitem = wi

      fe = @fexp
      fexp = @fexp
      flow_expression = @fexp
      fei = @fexp.fei
        #
        # some simple notations made available to ${ruby:...}
        # notations

      @fexp.context.treechecker.check(ruby_code)

      # clear for eval...

      eval(ruby_code, binding()).to_s
    end