code: def box_area(boxes):
      assert (boxes[:, 2:] >= boxes[:, :2]).all()
      wh = boxes[:, 2:] - boxes[:, :2]
      return wh[:, 0] * wh[:, 1]
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from scipy.optimize import linear_sum_assignment
  import paddle
  import paddle.nn
  import paddle.nn.functional
  from paddle.metric import accuracy
  from ppdet.core.workspace import register
  from ppdet.modeling.losses.iou_loss import GIoULoss
label_desc: Use image node_id 1 for calling a global function with example usage: box_area(boxes) and returns: unknown