This issue was brought up here (lfortran/lfortran#3432 (comment))

We were lucky to not have encountered this issue in Lpython itself. Consider the following

def main0():
    x: S = Symbol('x')
    y: S = Symbol('y')
    z: S = x + y
    print(z.func == Add)

main0()

So this is an example which is solved by the code in consideration