code: def sign(ctx, file, account):
      
      if not file:
          print_message("Prompting for message. Terminate with CTRL-D", "info")
          file = click.get_text_stream("stdin")
      m = Message(file.read(), bitshares_instance=ctx.bitshares)
      print_message(m.sign(account), "info")
docs: Sign a message with an account