code: def add(self, key, value):
          
          if isinstance(value, list):
              # TODO: support env vars in list w/masked values
              for val in value:
                  self._add_arg_python(key, val)
          elif isinstance(value, dict):
              err = 'Dictionary types are not currently supported for field.'
              print('{}{}{}'.format(c.Style.BRIGHT, c.Fore.RED, err))
          else:
              mask = False
              env_var = re.compile(r'^\$env\.(.*)$')
              envs_var = re.compile(r'^\$envs\.(.*)$')
  
              if env_var.match(str(value)):
                  # read value from environment variable
                  env_key = env_var.match(str(value)).groups()[0]
                  value = os.environ.get(env_key, value)
              elif envs_var.match(str(value)):
                  # read secure value from environment variable
                  env_key = envs_var.match(str(value)).groups()[0]
                  value = os.environ.get(env_key, value)
                  mask = True
              self._add_arg(key, value, mask)
docs: Add CLI Arg to lists value.
  
          Args:
              key (string): The CLI Args key (e.g., --name).
              value (string): The CLI Args value (e.g., bob).