code: def polygon_area(pr, pc):
      """Compute the area of a polygon.
  
      Parameters
      ----------
      pr, pc : (K,) array of float
          Polygon row and column coordinates.
  
      Returns
      -------
      a : float
          Area of the polygon.
      """
      pr = np.asarray(pr)
      pc = np.asarray(pc)
      return 0.5 * np.abs(
          np.sum((pc[:-1] * pr[1:]) - (pc[1:] * pr[:-1]))
      )
  
label_desc: Use image node_id 2 for calling a global function with example usage: polygon_area(pr, pc) and returns: unknown