human
Solve the following python programming problem given the following code:
def _print_Mul(self, expr) : 
    if (expr.is_number and expr.is_imaginary and expr.as_coeff_Mul () [0].is_integer) : 
        return ('%si' % self._print (((- S.ImaginaryUnit) * expr))) 
prec = precedence (expr) 
    (c, e) = expr.as_coeff_Mul () 
    if (c < 0) : 
        expr = _keep_coeff ((- c), e) 
        sign = '-' 
else : 
        sign = '' 
a = [] 
    b = [] 
    if (self.order not in ('old', 'none')) : 
        args = expr.as_ordered_factors () 
else : 
        args = Mul.make_args (expr) 
for item in args : 
        if (item.is_commutative and bi.is_Pow and item.exp.is_Rational and item.exp.is_negative) : 
            if (item.exp != (- 1)) : 
                b.append (Pow (item.base, (- item.exp), evaluate = False)) 
else : 
                b.append (Pow (item.base, (- item.exp))) 
else : 
            if (item.is_Rational and (item is not S.Infinity)) : 
                if (item.p != 1) : 
                    a.append (Rational (item.p)) 
if (item.q != 1) : 
                    b.append (Rational (item.q)) 
else : 
                a.append (item) 
a = (a or [S.One]) 
    a_str = [self.parenthesize (x, prec) for x in a] 
    b_str = [self.parenthesize (x, prec) for x in b] 
    def multjoin(a, a_str) : 
        r = a_str [0] 
        for i in range (1, len (a)) : 
            mulsym = ('*' if a [(i - 1)].is_number else '.*') 
            r = ((r + mulsym) + a_str [i]) 
return r 
if (len (b) == 0) : 
        return (sign + multjoin (a, a_str)) 
else : 
        if (len (b) == 1) : 
            divsym = ('/' if b [0].is_number else './') 
            return (((sign + multjoin (a, a_str)) + divsym) + b_str [0]) 
else : 
            divsym = ('/' if all ([bi.is_number for bi in b]) else './') 
            return (((sign + multjoin (a, a_str)) + divsym) + ('(%s)' % multjoin (b, b_str))) 

    
    

    Fix the buggy line: if (item.is_commutative and bi.is_Pow and item.exp.is_Rational and item.exp.is_negative) :
assistant
#Here is Python program to fix the buggy line: if (item.

if (item.is_commutative and item.is_Pow and item.exp.is_Rational and item.exp.is_negative) :