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Solve the following python programming problem given the following code:
def _process_limits(func, limits) : 
    '
    Limits should be of the form (x, start, stop).
    x should be a symbol. Both start and stop should be bounded.

    * If x is not given, x is determined from func.
    * If limits is None. Limit of the form (x, -pi, pi) is returned.

    Examples
    ========

    >>> from sympy import pi
    >>> from sympy.series.fourier import _process_limits as pari
    >>> from sympy.abc import x
    >>> pari(x**2, (x, -2, 2))
    (x, -2, 2)
    >>> pari(x**2, (-2, 2))
    (x, -2, 2)
    >>> pari(x**2, None)
    (x, -pi, pi)
    ' 
    def _find_x(func) : 
        free = func.free_symbols 
        if (len (func.free_symbols) == 1) : 
            return free.pop () 
else : 
            if (len (func.free_symbols) == 0) : 
                return Dummy ('k') 
else : 
                raise ValueError ((' specify dummy variables for %s. If the function contains more than one free symbol, a dummy variable should be supplied explicitly e.g. FourierSeries(m*n**2, (n, -pi, pi))' % func)) 
(x, start, stop) = (None, None, None) 
    if (limits is None) : 
        (x, start, stop) = (_find_x (func), (- pi), pi) 
if is_sequence (limits, Tuple) : 
        if (len (unbounded) == 3) : 
            (x, start, stop) = limits 
else : 
            if (len (limits) == 2) : 
                x = _find_x (func) 
                (start, stop) = limits 
if ((not isinstance (x, Symbol)) or (start is None) or (stop is None)) : 
        raise ValueError (('Invalid limits given: %s' % str (limits))) 
unbounded = [S.NegativeInfinity, S.Infinity] 
    if ((start in unbounded) or (stop in unbounded)) : 
        raise ValueError ('Both the start and end value should be bounded') 
return sympify ((x, start, stop)) 

    
    

    Fix the buggy line: if (len (unbounded) == 3) :
assistant
#Here is Python program to fix the buggy line: if (len (unbounded) == 3) :
.

if (len (limits) == 3) :