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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 _setup_arm_arch(self, arch_mode=None):
 """Set up ARM architecture. """

        if arch_mode is None:
            arch_mode = ARCH_ARM_MODE_THUMB

        self.name = "ARM"
        self.arch_info = ArmArchitectureInformation(arch_mode)
        self.disassembler = ArmDisassembler(architecture_mode=arch_mode)
        self.ir_translator = ArmTranslator(architecture_mode=arch_mode)