fix python 3.8 compatibility

reduct/bucket.py

@@ -178,7 +178,7 @@ async def remove_entry(self, entry_name: str):
     async def read(
         self,
         entry_name: str,
-        timestamp: Optional[int | datetime | float | str] = None,
+        timestamp: Optional[Union[int, datetime, float, str]] = None,
         head: bool = False,
     ) -> Record:
         """
@@ -209,7 +209,7 @@ async def write(
         self,
         entry_name: str,
         data: Union[bytes, AsyncIterator[bytes]],
-        timestamp: Optional[int | datetime | float | str] = None,
+        timestamp: Optional[Union[int, datetime, float, str]] = None,
         content_length: Optional[int] = None,
         **kwargs,
     ):
@@ -306,8 +306,8 @@ async def iter_body():
     async def query(
         self,
         entry_name: str,
-        start: Optional[int | datetime | float | str] = None,
-        stop: Optional[int | datetime | float | str] = None,
+        start: Optional[Union[int, datetime, float, str]] = None,
+        stop: Optional[Union[int, datetime, float, str]] = None,
         ttl: Optional[int] = None,
         **kwargs,
     ) -> AsyncIterator[Record]:
@@ -375,7 +375,7 @@ async def get_full_info(self) -> BucketFullInfo:
     async def subscribe(
         self,
         entry_name: str,
-        start: Optional[int | datetime | float | str] = None,
+        start: Optional[Union[int, datetime, float, str]] = None,
         poll_interval=1.0,
         **kwargs,
     ) -> AsyncIterator[Record]:

reduct/record.py

@@ -4,7 +4,16 @@
 from dataclasses import dataclass
 from datetime import datetime
 from functools import partial
-from typing import Dict, Callable, AsyncIterator, Awaitable, Optional, List, Tuple
+from typing import (
+    Dict,
+    Callable,
+    AsyncIterator,
+    Awaitable,
+    Optional,
+    List,
+    Tuple,
+    Union,
+)
 
 from aiohttp import ClientResponse
 
@@ -47,7 +56,7 @@ def __init__(self):
 
     def add(
         self,
-        timestamp: int | datetime | float | str,
+        timestamp: Union[int, datetime, float, str],
         data: bytes,
         content_type: Optional[str] = None,
         labels: Optional[Dict[str, str]] = None,

reduct/time.py

@@ -1,11 +1,12 @@
 """Helper functions for time-related operations."""
 
 from datetime import datetime
+from typing import Union
 
 TIME_PRECISION = 1_000_000
 
 
-def unix_timestamp_from_any(timestamp: int | datetime | float | str) -> int:
+def unix_timestamp_from_any(timestamp: Union[int, datetime, float, str]) -> int:
     """Convert timestamp to UNIX timestamp in microseconds
     Args:
         timestamp (int | datetime | float | str): int (UNIX timestamp in microseconds),