code: def _setup_arch(self, arch_mode=None):
          
          # set up architecture information
          self.arch_info = None
  
          if self.binary.architecture == ARCH_X86:
              self._setup_x86_arch(arch_mode)
          else:
              # TODO: add arch to the binary file class.
              self._setup_arm_arch(arch_mode)
docs: Set up architecture.