code: def parse_config(config, env, as_dict=True):
    
  
    if config is None:
      return None
    stripped = config.strip()
    if len(stripped) == 0:
      config = {}
    elif stripped[0] == '{':
      config = json.loads(config)
    else:
      config = yaml.load(config)
    if as_dict:
      config = dict(config)
  
    # Now we need to walk the config dictionary recursively replacing any '$name' vars.
    replace_vars(config, env)
    return config
docs: Parse a config from a magic cell body. This could be JSON or YAML. We turn it into
        a Python dictionary then recursively replace any variable references using the supplied
        env dictionary.