How to use the slicer.mrmlScene.Clear function in slicer

def setUp(self):
    """ Do whatever is needed to reset the state - typically a scene clear will be enough.
    """
    slicer.mrmlScene.Clear(0)
    #
    # first, get some data
    #
    import urllib
    downloads = (
        ('http://slicer.kitware.com/midas3/download?items=5768', 'tract1.vtk', slicer.util.loadFiberBundle),
        )

    for url,name,loader in downloads:
      filePath = slicer.app.temporaryPath + '/' + name
      if not os.path.exists(filePath) or os.stat(filePath).st_size == 0:
        print('Requesting download %s from %s...\n' % (name, url))
        urllib.urlretrieve(url, filePath)
      if loader:
        print('Loading %s...\n' % (name,))
        loader(filePath)

def setUp(self):
    """ Do whatever is needed to reset the state - typically a scene clear will be enough.
    """
    slicer.mrmlScene.Clear(0)

def setUp(self):
    """ Do whatever is needed to reset the state - typically a scene clear will be enough.
    """
    slicer.mrmlScene.Clear(0)

def setUp(self):
    """ Do whatever is needed to reset the state - typically a scene clear will be enough.
    """
    slicer.mrmlScene.Clear(0)

def setUp(self):
    """ Do whatever is needed to reset the state - typically a scene clear will be enough.
    """
    slicer.mrmlScene.Clear(0)