code: def distL2(x1,y1,x2,y2):
      
      xdiff = x2 - x1
      ydiff = y2 - y1
      return int(math.sqrt(xdiff*xdiff + ydiff*ydiff) + .5)
docs: Compute the L2-norm (Euclidean) distance between two points.
  
      The distance is rounded to the closest integer, for compatibility
      with the TSPLIB convention.
  
      The two points are located on coordinates (x1,y1) and (x2,y2),
      sent as parameters