code: def get(self):
          
  
          self._cast = type([])
          source_value = os.getenv(self.env_name)
  
          # set the environment if it is not set
          if source_value is None:
              os.environ[self.env_name] = json.dumps(self.default)
              return self.default
  
          try:
              val = json.loads(source_value)
          except JSONDecodeError as e:
              click.secho(str(e), err=True, color='red')
              sys.exit(1)
          except ValueError as e:
              click.secho(e.message, err=True, color='red')
              sys.exit(1)
  
          if self.validator:
              val = self.validator(val)
  
          return val
docs: convert json env variable if set to list