Trying to write a python function with a default sympy symbol

I am trying to write a function that has a sympy symbol with a default value, but am not getting what I expect.

Here is my code

import sympy as sydef addtwo(y = sy.symbols('y', reals = True)):    return y + 2y = sy.symbols('y')x = addtwo()print(type(x))print(x)print(x.subs(y,1))

with output

<class 'sympy.core.add.Add'>y + 2y + 2

However, the code

y = sy.symbols('y')x = addtwo(y)print(x)print(x.subs(y,1))

gives the expected output

y + 23