text: #!/usr/bin/env python
  # Copyright 2020 The Pigweed Authors
  #
  # Licensed under the Apache License, Version 2.0 (the "License"); you may not
  # use this file except in compliance with the License. You may obtain a copy of
  # the License at
  #
  #     https://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  # License for the specific language governing permissions and limitations under
  # the License.
  """Simple example script that uses pw_rpc."""
  
  import argparse
  import os
  from pathlib import Path
  
  import serial  # type: ignore
  
  from pw_hdlc_lite.rpc import HdlcRpcClient
  
  # Point the script to the .proto file with our RPC services.
  PROTO = Path(os.environ['PW_ROOT'], 'pw_rpc/pw_rpc_protos/echo.proto')
  
  
  def script(device: str, baud: int) -> None:
      # Set up a pw_rpc client that uses HDLC.
      client = HdlcRpcClient(serial.Serial(device, baud), [PROTO])
  
      # Make a shortcut to the EchoService.
      echo_service = client.rpcs().pw.rpc.EchoService
  
      # Call some RPCs and check the results.
      status, payload = echo_service.Echo(msg='Hello')
  
      if status.ok():
          print('The status was', status)
          print('The payload was', payload)
      else:
          print('Uh oh, this RPC returned', status)
  
      status, payload = echo_service.Echo(msg='Goodbye!')
  
      print('The device says:', payload.msg)
  
  
  def main():
      parser = argparse.ArgumentParser(
          description=__doc__,
          formatter_class=argparse.ArgumentDefaultsHelpFormatter)
      parser.add_argument('--device',
                          '-d',
                          default='/dev/ttyACM0',
                          help='serial device to use')
      parser.add_argument('--baud',
                          '-b',
                          type=int,
                          default=115200,
                          help='baud rate for the serial device')
      script(**vars(parser.parse_args()))
  
  
  if __name__ == '__main__':
      main()
  