class_docstr: Image database.
class_docstr_tok: ["Image","database","."]
code: def num_images(self):
      return len(self.image_index)
  
imports: import os
  import os.path
  import PIL
  import numpy
  import scipy.sparse
  from builtins import range
  import sys
  from .utils.cython_bbox import bbox_overlaps
label_desc: Use image node_id 9 for calling the imdb obj's underlying member method code with example usage: obj.num_images() and returns: len