code: def test_strip_blank_lines(self):
      lines = ["   ", "  foo  ", "   "]
      expected_output = ["  foo  "]
  
      self.assertEqual(
          expected_output, docstrings._strip_blank_lines(lines)
      )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from fire import docstrings
  from fire import testutils
label_desc: Use image node_id 16 for calling the DocstringsTest obj's underlying member method code with example usage: obj.test_strip_blank_lines() without return types