Commands with no do_* method fall to here.

def default(self, line):
        ''' Commands with no do_* method fall to here. '''
        # Commands that fall through to this method are interpreted as FORTH,
        # and must be in upper case.
        if not line.isupper():
            print(self.style.error('Error: ', 'Unrecognized command.'))
            return

        if self.arm.is_connected():
            if self.wrapper:
                line = self.wrapper.wrap_input(line)
            self.arm.write(line)
            try:
                res = self.arm.read()
            except KeyboardInterrupt:
                # NOTE interrupts aren't recursively handled.
                self.arm.write('STOP')
                res = self.arm.read()
            if self.wrapper:
                res = self.wrapper.wrap_output(res)
            print(res)
        else:
            print(self.style.error('Error: ', 'Arm is not connected.'))