human
Solve the following python programming problem given the following code:
def _exponents(expr, x) : 
    '
    Find the exponents of ``x`` (not including zero) in ``expr``.

    >>> from sympy.integrals.meijerint import _exponents
    >>> from sympy.abc import x, y
    >>> from sympy import sin
    >>> _exponents(x, x)
    set([1])
    >>> _exponents(x**2, x)
    set([2])
    >>> _exponents(x**2 + x, x)
    set([1, 2])
    >>> _exponents(x**3*sin(x + x**y) + 1/x, x)
    set([-1, 1, 3, y])
    ' 
    def _exponents_(expr, x, res) : 
        if (expr == x) : 
            res.update ([1]) 
            return 
if (expr.is_Pow and (expr.base == x)) : 
            res.update ([expr.exp]) 
            return 
for arg in expr.args : 
            _exponents_ (arg, x, res) 
res = set () 
    _exponents_ (expr, res, res) 
    return res 

    
    

    Fix the buggy line: _exponents_ (expr, res, res)
assistant
#Here is Python code to find the exponents of ``x`` (not including zero) in ``expr``.

_exponents_ (expr, x, res)