code: def visit_BitVecAdd(self, expression, *operands):
          
          left = expression.operands[0]
          right = expression.operands[1]
          if isinstance(right, BitVecConstant):
              if right.value == 0:
                  return left
          if isinstance(left, BitVecConstant):
              if left.value == 0:
                  return right
docs: a + 0  ==> a
              0 + a  ==> a