How does this code give me 17? (python)
j = 3
z = {}
z[2] = 1
z[7] = 3
z[5] = 2
for l in z:
j += l
print(j)

I don't understand where the 17 is coming from. I thought the square brackers where basically accessing the location (meaning the code would be like this "1, 2, 3." I even thought of individually adding 3 separately to all the numbers only for it to give me 15. Yeah, i've trying to understand this for 2 days lol.