class_docstr: Tensor representation of a list of Instances object for a batch of images.
  
  When dealing with a batch of images with Caffe2 ops, a list of bboxes
  (instances) are usually represented by single Tensor with size
  (sigma(Ni), 5) or (sigma(Ni), 4) plus a batch split Tensor. This class is
  for providing common functions to convert between these two representations.
class_docstr_tok: ["Tensor","representation","of","a","list","of","Instances","object","for","a","batch","of","images",".","When","dealing","with","a","batch","of","images","with","Caffe2","ops",",","a","list","of","bboxes","(","instances",")","are","usually","represented","by","single","Tensor","with","size","(","sigma","(","Ni",")",",","5",")","or","(","sigma","(","Ni",")",",","4",")","plus","a","batch","split","Tensor",".","This","class","is","for","providing","common","functions","to","convert","between","these","two","representations","."]
code: def has(self, name):
      return name in self.batch_extra_fields
  
imports: import math
  from typing import Dict
  import torch
  import torch.nn.functional
  from detectron2.layers import ShapeSpec, cat
  from detectron2.layers.roi_align_rotated import ROIAlignRotated
  from detectron2.modeling import poolers
  from detectron2.modeling.proposal_generator import rpn
  from detectron2.modeling.roi_heads.mask_head import mask_rcnn_inference
  from detectron2.structures import Boxes, ImageList, Instances, Keypoints, RotatedBoxes
  from .shared import alias, to_device
label_desc: Use image node_id 3 for calling the InstancesList obj's underlying member method code with example usage: obj.has(name) and returns: unknown