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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 _assemble_flowtable(self, values):
 """ generate a flowtable from a tuple of descriptors. """

        values = map(lambda x: [] if x is None else x, values)
        src = values[0] + values[1]
        dst = values[2] + values[3]

        thistable = dict()
        for s in src:
            thistable[s] = dst
        return thistable