code: def get_rendition_size(self, width=0, height=0):
          '''returns real rendition URL'''
          if width == 0 and height == 0:
              return (self.master_width, self.master_height)
  
          target_width = int(width)
          target_height = int(height)
  
          ratio = self.master_width / float(self.master_height)
          if target_height == 0 and target_width != 0:
              target_height = int(target_width / ratio)
  
          if target_height != 0 and target_width == 0:
              target_width = int(target_height * ratio)
  
          return target_width, target_heighf get_rendition_size(self, width=0, height=0):
          '''returns real rendition URL'''
          if width == 0 and height == 0:
              return (self.master_width, self.master_height)
  
          target_width = int(width)
          target_height = int(height)
  
          ratio = self.master_width / float(self.master_height)
          if target_height == 0 and target_width != 0:
              target_height = int(target_width / ratio)
  
          if target_height != 0 and target_width == 0:
              target_width = int(target_height * ratio)
  
          return target_width, target_height
docs: returns real rendition URL