docs: def _id(self):
          r"""
          The `SSHKey`'s ``id`` field, or if that is not defined, its
          ``fingerprint`` field.  If neither field is defined, accessing this
          attribute raises a `TypeError`.
          """
          if self.get("id") is not None:
              return self.id
          elif self.get("fingerprint") is not None:
              return self.fingerprint
          else:
              raise TypeError('SSHKey has neither .id nor .fingerprint')