code: def get_rendition_url(self, width=0, height=0):
          '''get the rendition URL for a specified size
  
          if the renditions does not exists it will be created
          '''
          if width == 0 and height == 0:
              return self.get_master_url()
  
          target_width, target_height = self.get_rendition_size(width, height)
  
          key = '%sx%s' % (target_width, target_height)
          if not self.renditions:
              self.renditions = {}
          rendition_name = self.renditions.get(key, False)
          if not rendition_name:
              rendition_name = self.make_rendition(target_width, target_height)
          return default_storage.url(rendition_namef get_rendition_url(self, width=0, height=0):
          '''get the rendition URL for a specified size
  
          if the renditions does not exists it will be created
          '''
          if width == 0 and height == 0:
              return self.get_master_url()
  
          target_width, target_height = self.get_rendition_size(width, height)
  
          key = '%sx%s' % (target_width, target_height)
          if not self.renditions:
              self.renditions = {}
          rendition_name = self.renditions.get(key, False)
          if not rendition_name:
              rendition_name = self.make_rendition(target_width, target_height)
          return default_storage.url(rendition_name)
docs: get the rendition URL for a specified size
  
          if the renditions does not exists it will be created