What does this code snippet in solo_head.py mean? I'm so confused.

[raintowing]

def points_nms(heat, kernel=2):  # kernel must be 2   hmax = nn.functional.max_pool2d(   heat, (kernel, kernel), stride=1, padding=1)   keep = (hmax[:, :, :-1, :-1] == heat).float()   return heat * keep