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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 sample(self, iter, length=None, verbose=0):
 """ Draws iter samples from the posterior. """

        self._cur_trace_index = 0
        self.max_trace_length = iter
        self._iter = iter
        self.verbose = verbose or 0
        self.seed()

        # Assign Trace instances to tallyable objects.
        self.db.connect_model(self)

        # Initialize database -> initialize traces.
        if length is None:
            length = iter
        self.db._initialize(self._funs_to_tally, length)

        # Put traces on objects
        for v in self._variables_to_tally:
            v.trace = self.db._traces[v.__name__]

        # Loop
        self._current_iter = 0
        self._loop()
        self._finalize()