Load and run an external FORTH script.

def do_run(self, arg):
        ''' Load and run an external FORTH script. '''
        if not self.arm.is_connected():
            print(self.style.error('Error: ', 'Arm is not connected.'))
            return

        # Load the script.
        try:
            with open(arg) as f:
                lines = [line.strip() for line in f.readlines()]
        except IOError:
            print(self.style.error('Error: ',
                                   'Could not load file \'{}\'.'.format(arg)))
            return

        for line in lines:
            if self.wrapper:
                line = self.wrapper.wrap_input(line)
            self.arm.write(line)
            res = self.arm.read()
            if self.wrapper:
                res = self.wrapper.wrap_output(res)
            print(res)