Why 'self' needed for patch and assert in Python?

I usually use:

def create_patch(self, name, value = None):
    patcher = patch(name)
    mock = patcher.start()
    mock.return_value = value
    self.addCleanup(patcher.stop)
    return mock

def assertXmlEqual(self, a, b):
    with open(a, 'r') as f:
        axml = f.read()
    with open(b, 'r') as f:
        bxml = f.read()
    self.assertEqual(loads(dumps((parse(axml)))), loads(dumps((parse(bxml)))))

and in testcases:

mockobj = self.create_patch('mymodule.myclass.mymethod', 'myvalue')

self.assertXmlEqual('expect.xml', 'result.xml')

But for every unit test class, I have to copy it.

Is there any way to make these more testcase-independent, more like a lib, like Moq and Assert in .net and mock and expect in Ruby?