docs: 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)