code: def saturation(
      im: np.ndarray, saturation_lower: float, saturation_upper: float
  ) -> np.ndarray:
      """
      Randomly disturb the saturation of the picture, user can use np.random.seed to fix the random behavior.
  
      Args:
          im(np.ndarray): Input image.
          saturation_lower(float): Lower bound of saturation.
          saturation_upper(float): Upper bound of saturation.
      """
      saturation_delta = np.random.uniform(
          saturation_lower, saturation_upper
      )
      im = PIL.ImageEnhance.Color(im).enhance(saturation_delta)
      return im
  
file_path: PaddleHub/paddlehub/vision/functional.py
imports: import os
  from typing import List, Union
  import cv2
  import PIL
  import numpy
label_desc: Use image node_id 9 for calling a global function with example usage: saturation(im, saturation_lower, saturation_upper) and returns: im