First pass EPP retry

src/epplibwrapper/errors.py

@@ -4,13 +4,15 @@ from enum import IntEnum
 class ErrorCode(IntEnum):
     """
     Overview of registry response codes from RFC 5730. See RFC 5730 for full text.
-
+        - 0 System connection error
         - 1000 - 1500 Success
         - 2000 - 2308 Registrar did something silly
         - 2400 - 2500 Registry did something silly
         - 2501 - 2502 Something malicious or abusive may have occurred
     """
 
+    TRANSPORT_ERROR = 0
+
     COMMAND_COMPLETED_SUCCESSFULLY = 1000
     COMMAND_COMPLETED_SUCCESSFULLY_ACTION_PENDING = 1001
     COMMAND_COMPLETED_SUCCESSFULLY_NO_MESSAGES = 1300
@@ -67,6 +69,9 @@ class RegistryError(Exception):
     def should_retry(self):
         return self.code == ErrorCode.COMMAND_FAILED
 
+    def is_transport_error(self):
+        return self.code == ErrorCode.TRANSPORT_ERROR
+
     # connection errors have error code of None and [Errno 99] in the err message
     def is_connection_error(self):
         return self.code is None