code: def get_example(self, i):
      n_inst = 2
      img = np.random.randint(0, 256, size=(3, self.H, self.W))
      n_point = np.random.choice(self.n_point_candidates)
      point_y = np.random.uniform(0, self.H, size=(n_inst, n_point))
      point_x = np.random.uniform(0, self.W, size=(n_inst, n_point))
      point = np.stack((point_y, point_x), axis=2).astype(np.float32)
      if self.return_visible:
          visible = np.random.randint(
              0, 2, size=(n_inst, n_point)
          ).astype(np.bool)
          return (img, point, visible) + self.options
      else:
          return (img, point) + self.options
  
imports: import numpy
  import unittest
  from chainer.dataset import DatasetMixin
  from chainercv.utils import assert_is_point_dataset
  from chainercv.utils import testing
label_desc: Use image node_id 3 for calling the PointDataset obj's underlying member method code with example usage: obj.get_example(i) and returns: unknown, unknown