Python: .join method

Question

def func(x):
for i in range(x):
yield i**2
print(",".join(list(func(3))))

# outputs TypeError: sequence item 0: expected str instance, int found

The join() method takes all items in an iterable and joins them into one string.
So I instead tried converting the func to a string instead:

def func(x):
for i in range(x):
yield i**2
print(",".join(list(str(func(3)))))

#outputs <,g,e,n,e,r,a,t,o,r, ,o,b,j,e,c,t, ,f,u,n,c, ,a,t, ,0,x,7,f,f,4,6,a,6,4,f,3,5,0,>

Why did this happen?
How can I simply get 0,1,4 or [0,1,4] or ["0", "1", "4"] as intended?

Answer 1

yield str(i**2)