code: def ball_query_square(
      N: int,
      P1: int,
      P2: int,
      D: int,
      K: int,
      radius: float,
      device: str,
  ):
      device = torch.device(device)
      pts1 = torch.randn(N, P1, D, device=device, requires_grad=True)
      pts2 = torch.randn(N, P2, D, device=device, requires_grad=True)
      grad_dists = torch.randn(N, P1, K, device=device)
      torch.cuda.synchronize()
  
      def output():
          out = ball_query(pts1, pts2, K=K, radius=radius)
          loss = (out.dists * grad_dists).sum()
          loss.backward()
          torch.cuda.synchronize()
  
      return output
  
imports: import unittest
  from itertools import product
  import torch
  from pytorch3d.ops import sample_points_from_meshes
  from pytorch3d.ops.ball_query import ball_query
  from pytorch3d.ops.knn import _KNN
  from pytorch3d.utils import ico_sphere
  from .common_testing import get_random_cuda_device, TestCaseMixin
label_desc: Use image node_id 10 for calling the TestBallQuery obj's underlying member method code with example usage: obj.ball_query_square(N, P1, P2, D, K, radius, device) and returns: output