applications.collages.collageAlgebra:
  {
  
    sq = { filledPolygon((0,0),(12,0),(12,12),(0,12)) },
            
    f1 = scale(1/4,1/2),
    f2 = scale(1/4) . translate(3,6),
    f3 = scale(1/2,1/4) . translate(6,9),
    f4 = scale(1/2) . translate(6,0),
    F = <f1,f2,f3,f4>
    
  }
