Get a command from the user and respond to it.

def interact(self):
        """Get a command from the user and respond to it."""
        lines = ""
        for line in self.read():
            lines += line
            try:
                self.eval(lines)
            except ValueError:
                pass
            except KeyboardInterrupt as e:
                raise e
            except:
                self.terminal.error(traceback.format_exc())
                break
            else:
                break