Return a list of conditional statement exits with respect to a basic block.

        :param block_addr:  The address of the basic block.
        :return:            A list of statement IDs.

def _conditional_exits(self, block_addr):
        """
        Return a list of conditional statement exits with respect to a basic block.

        :param block_addr:  The address of the basic block.
        :return:            A list of statement IDs.
        """

        vex_block = self.project.factory.block(block_addr).vex
        lst = [ ]

        for i, stmt in enumerate(vex_block.statements):
            if isinstance(stmt, pyvex.IRStmt.Exit):
                lst.append(i)

        return lst