code: def testFnFishScript(self):
      script = completion.Script("identity", tc.identity, shell="fish")
      self.assertIn("arg1", script)
      self.assertIn("arg2", script)
      self.assertIn("arg3", script)
      self.assertIn("arg4", script)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from fire import completion
  from fire import test_components
  from fire import testutils
label_desc: Use image node_id 12 for calling the TabCompletionTest obj's underlying member method code with example usage: obj.testFnFishScript() without return types