Use syntax compatible with Python 3.8 and 3.9

eventkit/event.py

@@ -536,7 +536,7 @@ def aiterate(ait: AsyncIterable) -> "Aiterate":
     @staticmethod
     def sequence(
             values: Iterable, interval: float = 0,
-            times: Iterable[float] | None = None) -> "Sequence":
+            times: Union[Iterable[float], None] = None) -> "Sequence":
         """
         Create a new event that emits the given values.
         Supply at most one ``interval`` or ``times``.
@@ -552,7 +552,7 @@ def sequence(
     @staticmethod
     def repeat(
             value=NO_VALUE, count=1, interval: float = 0,
-            times: Iterable[float] | None = None) -> "Repeat":
+            times: Union[Iterable[float], None] = None) -> "Repeat":
         """
         Create a new event that repeats ``value`` a number of ``count`` times.
 
@@ -568,7 +568,7 @@ def repeat(
     @staticmethod
     def range(
             *args, interval: float = 0,
-            times: Iterable[float] | None = None) -> "Range":
+            times: Union[Iterable[float], None] = None) -> "Range":
         """
         Create a new event that emits the values from a range.
 
@@ -604,7 +604,7 @@ def timerange(start=0, end=None, step=1) -> "Timerange":
         return Timerange(start, end, step)
 
     @staticmethod
-    def timer(interval: float, count: int | None = None) -> "Timer":
+    def timer(interval: float, count: Union[int, None] = None) -> "Timer":
         """
         Create a new timer event that emits at regularly paced intervals
         the number of seconds since starting it.
@@ -618,7 +618,7 @@ def timer(interval: float, count: int | None = None) -> "Timer":
     @staticmethod
     def marble(
             s: str, interval: float = 0,
-            times: Iterable[float] | None = None) -> "Marble":
+            times: Union[Iterable[float], None] = None) -> "Marble":
         """
         Create a new event that emits the values from a Rx-type marble string.
 
@@ -1001,7 +1001,8 @@ def all(self) -> "All":
         """
         return All(self)
 
-    def ema(self, n: int | None = None, weight: float | None = None) -> "Ema":
+    def ema(self, n: Union[int, None] = None,
+            weight: Union[float, None] = None) -> "Ema":
         """
         Exponential moving average.
 

eventkit/ops/op.py

@@ -1,3 +1,5 @@
+from typing import Union
+
 from ..event import Event
 
 
@@ -17,7 +19,7 @@ class Op(Event):
 
     __slots__ = ()
 
-    def __init__(self, source: Event | None = None):
+    def __init__(self, source: Union[Event, None] = None):
         Event.__init__(self)
         if source is not None:
             self.set_source(source)