code: def eq(self, r1, r2):
          
          if not is_register(r1) or not is_register(r2):
              return False
  
          if self.regs[r1] is None or self.regs[r2] is None:  # HINT: This's been never USED??
              return False
  
          return self.regs[r1] == self.regs[r2]
docs: True if values of r1 and r2 registers are equal