human
Solve the following python programming problem given the following code:
def qsimplify(expr) : 
    '
    Simplify expression by recursively evaluating the quantity arguments.

    If units are encountered, as it can be when using Constant, they are
    converted to quantity.
    ' 
    def redmul(x, y) : 
        '
        Function used to combine args in multiplications.

        This is necessary because the previous computation was not commutative,
        and Mul(3, u) was not simplified.
but Mul(u, 3) was.
        ' 
        if isinstance (x, Quantity) : 
            return x.mul (y) 
else : 
            if isinstance (y, Quantity) : 
                return y.mul (x) 
else : 
                return (x * y) 
args = [] 
    for arg in expr.args : 
        arg = arg.evalf () 
        if isinstance (arg, (Mul, Pow, Add)) : 
            arg = qsimplify (arg) 
args.append (arg) 
(q_args, o_args) = ([], []) 
    for arg in args : 
        if isinstance (arg, Quantity) : 
            q_args.append (arg) 
else : 
            if isinstance (arg, Unit) : 
                q_args.append (arg.as_quantity) 
else : 
                o_args.append (arg) 
if isinstance (expr, Pow) : 
        return args [0].pow (args [1]) 
else : 
        if isinstance (expr, Add) : 
            if (q_args != []) : 
                quantities = reduce ((lambda x, y : x.add (y)), q_args) 
else : 
                quantities = [] 
return reduce ((lambda x, y : (x + y)), o_args, quantities) 
else : 
            if isinstance (expr, Mul) : 
                if (q_args != []) : 
                    quantities = reduce ((lambda x, y : x.mul (y)), arg) 
else : 
                    quantities = [] 
return reduce (redmul, o_args, quantities) 
else : 
                return expr 

    
    

    Fix the buggy line: quantities = reduce ((lambda x, y : x.mul (y)), arg)
assistant
#Here is Python program to fix the buggy line: quantities = reduce ((lambda x, y : x.

quantities = reduce ((lambda x, y : x.mul (y)), q_args)