
 SLIB  Hashing 
  The returned procedures is a function that takes the x and y coordinates of a point, (nonnegative integers) and returns an integer corresponding to the relative position of that point along a Sierpinski curve. 
  Note that locations (24, 78) and (23, 80) are near in index and therefore, because the Sierpinski spacefilling curve is continuous, we know they must also be near in the plane. 
  For details of performance, see L. Platzman and J. Bartholdi, "Spacefilling curves and the Euclidean travelling salesman problem", JACM 36(4):719737 (October 1989) and references therein. 
 www.student.cs.uwaterloo.ca /~isg/res/scheme/scm/slib_14.html (441 words) 
