text: import xml.etree.ElementTree as ET
  from os import getcwd
  
  sets=[('2007', 'train'), ('2007', 'val'), ('2007', 'test')]
  
  classes = ["license_plate"]
  
  def convert_annotation(year, image_id, list_file):
      in_file = open('VOC%s/Annotations/%s.xml'%(year, image_id))
      tree=ET.parse(in_file)
      root = tree.getroot()
  
      for obj in root.iter('object'):
          difficult = obj.find('difficult').text
          cls = obj.find('name').text
          if cls not in classes or int(difficult)==1:
              continue
          cls_id = classes.index(cls)
          xmlbox = obj.find('bndbox')
          b = (int(xmlbox.find('xmin').text), int(xmlbox.find('ymin').text), int(xmlbox.find('xmax').text), int(xmlbox.find('ymax').text))
          list_file.write(" " + ",".join([str(a) for a in b]) + ',' + str(cls_id))
  
  wd = getcwd()
  
  for year, image_set in sets:
      image_ids = open('VOC%s/ImageSets/Main/%s.txt'%(year, image_set)).read().strip().split()
      list_file = open('%s_%s.txt'%(year, image_set), 'w')
      for image_id in image_ids:
          list_file.write('%s/VOC%s/JPEGImages/%s.jpg'%(wd, year, image_id))
          convert_annotation(year, image_id, list_file)
          list_file.write('\n')
      list_file.close()
  
  