TypeError：“ NoneType”对象不可调用（初学者）Python

Question

It tells me there is an AssertionError in line 11.I'm new to programming, not sure if this helps.The code is supposed to give me the i-th element of the x-th row, so for row3(3) = 9 for row4(10) = 40.

def multiplicationtable(x):

    def row(i):
        print (x * i)
    return row

row3 = multiplicationtable(3)

assert row3(3) == 9

AssertionError Traceback (most recent call last) in

10 row3 = multiplicationtable(3)

---> 11 assert row3(3) == 9

AssertionError:

Answer 1

You are getting AssertionError because row(i) function is not returning any value. It should be written in this way:

def multiplicationtable(x):

    def row(i):
        print (x * i)
        return x * i
    return row
row3 = multiplicationtable(3)

assert row3(3) == 9