Why is there a "." before join? And why is it 24 eventually?

Question

What is the output of the code?
def f(r):
j = range (1, r + 1)
return eval("*".joint([str(i) for i in j]))
print(f(4))

Answer 1

joint????

1*2*3*4 = 24

Answer 2

sorry "join"