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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 ret(self, expr=None):
 """ Add an exit representing a return from this function. If this is not an inline call, grab a return address from the state and jump to it. If this is not an inline call, set a return expression with the calling convention. """

        self.inhibit_autoret = True

        if expr is not None:
            if o.SIMPLIFY_RETS in self.state.options:
                l.debug("... simplifying")
                l.debug("... before: %s", expr)
                expr = self.state.solver.simplify(expr)
                l.debug("... after: %s", expr)

            if self.symbolic_return:
                size = len(expr)
                new_expr = self.state.solver.Unconstrained(
                        "symbolic_return_" + self.display_name,
                        size,
                        key=('symbolic_return', self.display_name)) #pylint:disable=maybe-no-member
                self.state.add_constraints(new_expr == expr)
                expr = new_expr

            self.ret_expr = expr

        ret_addr = None
        # TODO: I had to put this check here because I don't understand why self.use_state_arguments gets reset to true
        # when calling the function ret. at the calling point the attribute is set to False
        if isinstance(self.addr, SootAddressDescriptor):
            ret_addr = self._compute_ret_addr(expr)
        elif self.use_state_arguments:
            ret_addr = self.cc.teardown_callsite(
                    self.state,
                    expr,
                    arg_types=[False]*self.num_args if self.cc.args is None else None)

        if not self.should_add_successors:
            l.debug("Returning without setting exits due to 'internal' call.")
            return

        if self.ret_to is not None:
            ret_addr = self.ret_to

        if ret_addr is None:
            raise SimProcedureError("No source for return address in ret() call!")

        self._prepare_ret_state()

        self._exit_action(self.state, ret_addr)
        self.successors.add_successor(self.state, ret_addr, self.state.solver.true, 'Ijk_Ret')