new_contents: #!/usr/bin/env python3
  
  import sys
  
  import curio
  import curio.socket
  
  
  async def server(address):
      sock = curio.socket.socket(curio.socket.AF_INET, curio.socket.SOCK_STREAM)
      sock.setsockopt(curio.socket.SOL_SOCKET, curio.socket.SO_REUSEADDR, 1)
      sock.bind(address)
      sock.listen(5)
      print('Listen at', address)
      async with sock:
          while True:
              conn, addr = await sock.accept()
              await curio.spawn(handler(conn, addr))
  
  
  async def handler(conn, address):
      print('Connection from', address)
      async with conn:
          while True:
              data = await conn.recv(256)
              if not data:
                  break
              await conn.sendall(data)
      print('Connection closed')
  
  
  def main(argv):
      curio.run(server(('', 25000)))
      return 0
  
  
  if __name__ == '__main__':
      sys.exit(main(sys.argv))
  
subject: Add prototypical curio/echo_server.py