how to explain and understand s[np.array(util.limbSeq[i]) - 1] ? can we use util.limbSeq[i]) - 1 to replace the s[np.array(util.limbSeq[i]) - 1]

[Ai-is-light]

I'm a little bit confused when I run and analysis your repo
for i in range(17):
for s in subset:
index = s[np.array(util.limbSeq[i]) - 1]
if -1 in index:
continue
cur_canvas = canvas.copy()

how to explain and understand s[np.array(util.limbSeq[i]) - 1] ? can we use util.limbSeq[i]) - 1 to replace the s[np.array(util.limbSeq[i]) - 1] ?
I guess if all the keypoints of one person detected, they will get the same result ?
if s = [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 31.90218401323376, 18.0], and how to understand the 0.0, 31.90218401323376, 18.0 and others(1.0, 2.0, 3.0, 4.0,...)?
@michalfaber
Thanks

[Ai-is-light]

I mean s = [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 31.90218401323376, 18.0], which is one subset of all subsets of person detected. Both 31.90218401323376 and 18.0 stand for the background?
@michalfaber