class_docstr: [OpenAI Retro](https://github.com/openai/retro) environment adapter (specification key:
  `retro`, `openai_retro`).
  
  May require:
  ```bash
  pip3 install gym-retro
  ```
  
  Args:
      level (string): Game id
          (<span style="color:#C00000"><b>required</b></span>).
      visualize (bool): Whether to visualize interaction
          (<span style="color:#00C000"><b>default</b></span>: false).
      monitor_directory (string): Monitor output directory
          (<span style="color:#00C000"><b>default</b></span>: none).
      kwargs: Additional Retro environment arguments.
class_docstr_tok: ["[","OpenAI","Retro","]","(","https",":","\/\/github.com\/openai\/retro",")","environment","adapter","(","specification","key",":","`","retro","`",",","`","openai_retro","`",")",".","May","require",":","``","`","bash","pip3","install","gym-retro","``","`","Args",":","level","(","string",")",":","Game","id","(","<","span","style=","''","color",":","#","C00000","''",">","<","b",">","required","<","\/b",">","<","\/span",">",")",".","visualize","(","bool",")",":","Whether","to","visualize","interaction","(","<","span","style=","''","color",":","#","00C000","''",">","<","b",">","default","<","\/b",">","<","\/span",">",":","false",")",".","monitor_directory","(","string",")",":","Monitor","output","directory","(","<","span","style=","''","color",":","#","00C000","''",">","<","b",">","default","<","\/b",">","<","\/span",">",":","none",")",".","kwargs",":","Additional","Retro","environment","arguments","."]
code: def levels(cls):
      import retro
  
      return list(retro.data.list_games())
  
imports: from tensorforce.environments import OpenAIGym
label_desc: Use image node_id 1 for calling the OpenAIRetro obj's underlying member method code with example usage: obj.levels(cls) and returns: list