usys: Add examples.

doc/main/micropython/usys.rst

@@ -16,4 +16,14 @@ This MicroPython module is a subset of the `sys module`_ in Python.
 .. autodata:: usys.stderr
     :annotation:
 
+Examples
+---------------
+
+The ``stdin`` stream can be used to capture input via the Pybricks Code
+input/output window. See the `keyboard input`_ project to learn how this works.
+This approach can be extended to exchange data with any `other device`_ as well.
+
+.. _keyboard input: https://pybricks.com/projects/tutorials/wireless/hub-to-device/pc-keyboard/
+.. _other device: https://pybricks.com/projects/tutorials/wireless/hub-to-device/
+
 .. _sys module: https://docs.python.org/3.5/library/sys.html

src/usys/__init__.py

@@ -11,14 +11,12 @@ This module provides a subset of the standard Python ``sys`` module.
 
 from uio import FileIO as _FileIO
 
-# REVISIT: most functions are excluded since they aren't useful for Pybricks
-
 stdin: _FileIO = _FileIO()
 """
-Stream object (:class:`uio.FileIO`) that receives input from a connected
+This is a stream object (:class:`uio.FileIO`) that receives input from a connected
 terminal, if any.
 
-Writing may modify newline characters. Use ``usys.stdin.buffer`` instead if
+Writing may modify newline characters. Use ``stdin.buffer`` instead if
 this is undesirable.
 
 Also see :func:`micropython.kbd_intr` to disable ``KeyboardInterrupt`` if you
@@ -27,10 +25,10 @@ are passing binary data via ``stdin``.
 
 stdout: _FileIO = _FileIO()
 """
-Stream object (:class:`uio.FileIO`) that sends output to a connected terminal,
+This is a stream object (:class:`uio.FileIO`) that sends output to a connected terminal,
 if any.
 
-Reading may modify newline characters. Use ``usys.stdout.buffer`` instead if
+Reading may modify newline characters. Use ``stdout.buffer`` instead if
 this is undesirable.
 """