applications.collages.collageAlgebra:
{
  ntColour = const(.8),

  line = { curve((-1,0) right (1.5,0),
                 (0,-.8) right (-.5,0),
                 (1,0) right (1.5,0)) },

  
  sample-outline = { polygon((-1,0),(1,0),(0,-1),(-1,0))},
  sample-filled = { filledPolygon((-1,0),(1,0),(0,-1),(-1,0))[#ntColour,#ntColour,#ntColour] }
                       + #sample-outline,
  sample-arrow = { filledPolygon((1,0),(.8,.05),(.8,-.05))},
  sample = #sample-filled + #sample-outline + #sample-arrow,
  S = #sample,
  
  f1 = similarity((-1,0) -> (-1,0), (1,0) -> (0,-1)),
  f2 = similarity((-1,0) -> (1,0), (1,0) -> (0,-1)),
  F = <f1, f2>
}