code: def source_url(farm, server, id, secret, size):
      ''' Url for direct jpg use. '''
      if size == 'small':
          img_size = 'n'
      elif size == 'medium':
          img_size = 'c'
      elif size == 'large':
          img_size = 'b'
  
      return 'https://farm{}.staticflickr.com/{}/{}_{}_{}.jpg'.format(
          farm, server, id, secret, img_sizef source_url(farm, server, id, secret, size):
      ''' Url for direct jpg use. '''
      if size == 'small':
          img_size = 'n'
      elif size == 'medium':
          img_size = 'c'
      elif size == 'large':
          img_size = 'b'
  
      return 'https://farm{}.staticflickr.com/{}/{}_{}_{}.jpg'.format(
          farm, server, id, secret, img_size)
docs: Url for direct jpg use.