class_docstr: Base class for instance masks.
class_docstr_tok: ["Base","class","for","instance","masks","."]
docstr: Convert masks to the format of ndarray.
  
  Return:
      ndarray: Converted masks in the format of ndarray.
docstr_tok: ["Convert","masks","to","the","format","of","ndarray",".","Return",":","ndarray",":","Converted","masks","in","the","format","of","ndarray","."]
code: def to_ndarray(self):
      """Convert masks to the format of ndarray.
  
      Return:
          ndarray: Converted masks in the format of ndarray.
      """
      pass
  
imports: from abc import ABCMeta, abstractmethod
  import cv2
  import mmcv
  import numpy
  import pycocotools.mask
  import torch
  from mmcv.ops.roi_align import roi_align
label_desc: Use image node_id 9 for calling the BaseInstanceMasks obj's underlying member method code with example usage: obj.to_ndarray() without return types