code: def reg(self):
          
          if self.type.is_displ or self.type.is_phrase:
              size = core.get_native_size()
              return base.get_register_name(self.reg_id, size)
  
          if self.type.is_reg:
              return base.get_register_name(self.reg_id, self.size)
  
          else:
              raise exceptions.SarkOperandWithoutReg("Operand does not have a register.")
docs: Name of the register used in the operand.