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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def can_persist_fixtures():
 """Returns True if it's possible to persist fixtures across tests. Flask-Fixtures uses the setUpClass and tearDownClass methods to persist fixtures across tests. These methods were added to unittest.TestCase in python 2.7. So, we can only persist fixtures when using python 2.7. However, the nose and py.test libraries add support for these methods regardless of what version of python we're running, so if we're running with either of those libraries, return True to persist fixtures. """

    # If we're running python 2.7 or greater, we're fine
    if sys.hexversion >= 0x02070000:
        return True

    # Otherwise, nose and py.test support the setUpClass and tearDownClass
    # methods, so if we're using either of those, go ahead and run the tests
    filename = inspect.stack()[-1][1]
    executable = os.path.split(filename)[1]
    return executable in ('py.test', 'nosetests')