code: def permission_string(self) -> str:
      if self.permission in COMPOUND_ACTION_PERMISSION:
          return f"{self.permission.name}"
      else:
          return f"{self.credentials.verify}_{self.permission.name}"
  
imports: from enum import Enum
  from typing import Optional
  from ...node.credentials import SyftVerifyKey
  from ...serde.serializable import serializable
  from ...types.uid import UID
label_desc: Use image node_id 2 for calling the ActionObjectPermission obj's underlying member method code with example usage: obj.permission_string() and returns: self, self, str, self