docs: protected void setResults(GraphRewrite event, String variable, Iterable<? extends WindupVertexFrame> results)
      {
          Variables variables = Variables.instance(event);
          Iterable<? extends WindupVertexFrame> existingVariables = variables.findVariable(variable, 1);
          if (existingVariables != null)
          {
              variables.setVariable(variable, Iterables.concat(existingVariables, results));
          }
          else
          {
              variables.setVariable(variable, results);
          }
      }