code: def prewitt_h(image, mask=None):
      """Find the horizontal edges of an image using the Prewitt transform.
  
      Parameters
      ----------
      image : 2-D array
          Image to process.
      mask : 2-D array, optional
          An optional mask to limit the application to a certain area.
          Note that pixels surrounding masked regions are also masked to
          prevent masked regions from affecting the result.
  
      Returns
      -------
      output : 2-D array
          The Prewitt edge map.
  
      Notes
      -----
      We use the following kernel::
  
        1/3   1/3   1/3
         0     0     0
       -1/3  -1/3  -1/3
  
      """
      check_nD(image, 2)
      return prewitt(image, mask=mask, axis=0)
  
imports: import numpy
  from scipy import ndimage
  from scipy.ndimage import binary_erosion, convolve
  from .._shared.utils import _supported_float_type, check_nD
  from ..restoration.uft import laplacian
  from ..util.dtype import img_as_float
label_desc: Use image node_id 12 for calling a global function with example usage: prewitt_h(image, mask) and returns: prewitt