Add pwmio.py for PWMOut Protocol

Author: tekktrik

circuitpython_typing/pwmio.py

@@ -0,0 +1,30 @@
+# SPDX-FileCopyrightText: Copyright (c) 2022 Alec Delaney
+#
+# SPDX-License-Identifier: MIT
+
+"""
+`circuitpython_typing.pwmio`
+================================================================================
+
+Type annotation definitions for PWMOut where Blinka doesn't otherwise define it.
+
+* Author(s): Alec Delaney
+"""
+
+# # Protocol was introduced in Python 3.8.
+try:
+    from typing import Union, Tuple, Protocol
+except ImportError:
+    from typing_extensions import Protocol
+
+class PWMOut(Protocol):
+    """Protocol that implements, at the bare minimum, the `duty_cycle` property"""
+
+    @property
+    def duty_cycle(self) -> int:
+        """The duty cycle as a ratio using 16-bits"""
+        ...
+
+    @duty_cycle.setter
+    def duty_cycle(self, duty_cycle: int) -> None:
+        ...