class_docstr: OTB Visual Tracker Benchmark.
  
  Parameters
  ----------
  name : str
      name to data, and name to dataset json Default is 'OTB2015'
  dataset_root: str
      path to dataset root
class_docstr_tok: ["OTB","Visual","Tracker","Benchmark",".","Parameters","--","--","--","--","--","name",":","str","name","to","data",",","and","name","to","dataset","json","Default","is","'OTB2015'","dataset_root",":","str","path","to","dataset","root"]
code: def __getitem__(self, idx):
      if isinstance(idx, str):
          return self.videos[idx]
      elif isinstance(idx, int):
          return self.videos[sorted(list(self.videos.keys()))[idx]]
      return None
  
imports: import json
  import os
  from glob import glob
  from tqdm import tqdm
  from mxnet.gluon.data import dataset
  from gluoncv.utils.filesystem import try_import_cv2
label_desc: Use image node_id 2 for calling the OTBTracking obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: None, self, self