old_contents: import sys
  
  import pytest
  
  version = tuple(sys.version_info[:2])
  
  class DummyCollector(pytest.File):
      def collect(self):
          return []
  
  def pytest_pycollect_makemodule(path, parent):
      if '_py33' in path.basename and version < (3, 3):
          return DummyCollector.from_parent(parent, fspath=path)
      if '_py37' in path.basename and version < (3, 7):
          return DummyCollector.from_parent(parent, fspath=path)
      if '_py3' in path.basename and version < (3, 0):
          return DummyCollector.from_parent(parent, fspath=path)
      if '_py2' in path.basename and version >= (3, 0):
          return DummyCollector.from_parent(parent, fspath=path)
  
new_contents: import sys
  
  import pytest
  
  version = tuple(sys.version_info[:2])
  
  class DummyCollector(pytest.File):
      def collect(self):
          return []
  
  def pytest_pycollect_makemodule(path, parent):
      if version < (3, 0):
          if '_py27' in path.basename:
              return DummyCollector(path, parent=parent)
      else:
          if '_py33' in path.basename and version < (3, 3):
              return DummyCollector.from_parent(parent, fspath=path)
          if '_py37' in path.basename and version < (3, 7):
              return DummyCollector.from_parent(parent, fspath=path)
          if '_py3' in path.basename and version < (3, 0):
              return DummyCollector.from_parent(parent, fspath=path)
          if '_py2' in path.basename and version >= (3, 0):
              return DummyCollector.from_parent(parent, fspath=path)
  
subject: configure conftest to work with python 2 and 3