docs: def contiguous(polygons):
          """
          Static method. Check whether a set of convex polygons are all 
  		contiguous. Two polygons are considered contiguous if they 
  		share, at least, one side (two vertices).
          
          This is not a complete verification, it is a very simplified
          one. For a given set of polygons this method will verify that 
          the number of common vertices among them equals or exceeds the
          minimum number of common vertices possible.
          
          This little algorithm will not declare a contiguous set of 
          polygons as non-contiguous, but it can fail in the reverse for 
          certain geometries where polygons have several common vertices
          among them.
          
          :param polygons: List of polygons.
          :type polygons: list of ``pyny.Polygon``
          :return: Whether tey are contiguous.
          :rtype: bool
          """
          from pyny3d.utils import sort_numpy
          
          n = len(polygons)
          points = sort_numpy(np.concatenate([polygon.points 
                                              for polygon in polygons]))
          diff = np.sum(np.diff(points, axis=0), axis=1)
          if sum(np.isclose(diff, 0)) < n*2-2:
              return False
          else:
              return True