code: def testFnCompletions(self):
      def example(one, two, three):
          return one, two, three
  
      completions = completion.Completions(example)
      self.assertIn("--one", completions)
      self.assertIn("--two", completions)
      self.assertIn("--three", completions)
  
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 3 for calling the TabCompletionTest obj's underlying member method code with example usage: obj.testFnCompletions() and returns: one,  two,  three