code: def signed_area(coords):
      """Return the signed area enclosed by a ring using the linear time
      algorithm at http://www.cgafaq.info/wiki/Polygon_Area. A value >= 0
      indicates a counter-clockwise oriented ring.
      """
      xs, ys = map(list, zip(*coords))
      xs.append(xs[1])
      ys.append(ys[1])
      return (
          sum(
              xs[i] * (ys[i + 1] - ys[i - 1])
              for i in range(1, len(coords))
          )
          / 2.0
      )
  
imports: import datetime
  import logging
  import sys
  import fiona
label_desc: Use image node_id 1 for calling a global function with example usage: signed_area(coords) and returns: unknown