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

  angle = { polyline((0,.8),(.8,.8),(.8,0)) },
    
  sample-outline = { polygon((0,0),(1,0),(1,1),(0,1))},
  sample-filled = { filledPolygon((0,0),(1,0),(1,1),(0,1))[#ntColour,#ntColour,#ntColour] }
                       + #sample-outline,
  R = #sample-filled + { filledPolygon((.7,.4),(1,.5),(.7,.6)) },
  T = #sample-filled + { filledPolygon((.4,.7),(.5,1),(.6,.7)) },
  C = #sample-filled + { filledPolygon((.7,.85),(1,1),(.85,.7)) },
    
  d1 = translate(0,1),
  d2 = translate(1,0),
  d3 = translate(1,1),
  diag = <#angle, d1, d2, d3>,
  
  up = translate(0,1),
  up = <#angle, up>,
  
  right = translate(1,0),
  right = <#angle, right>
  
}
