text: CREATE EXTENSION IF NOT EXISTS pg_plan_tree_dot;
  
  DROP TYPE IF EXISTS color;
  DROP TABLE IF EXISTS screen;
  
  CREATE TYPE color AS ENUM (
         'black',
         'white',
         'red',
         'green',
         'blue');
  
  CREATE TABLE screen (
         forecolor color,
         bgcolor color);
  
  INSERT INTO screen VALUES ('red',   'black');
  INSERT INTO screen VALUES ('white', 'black');
  INSERT INTO screen VALUES ('green', 'black');
  INSERT INTO screen VALUES ('blue',  'white');
  
  -- SELECT * FROM screen WHERE bgcolor = 'black';
  SELECT generate_plan_tree_dot('SELECT * FROM screen WHERE bgcolor = ''black'';', 'sample-enum-type.dot');
  
  DROP TABLE screen;
  DROP TYPE color;
  