gap> file:=Filename(DirectoriesPackageLibrary("HAP"),"../tutorial/images/circularGradient.png");;
gap> L:=[];;                                                          
gap> for n in [1..15] do
> M:=ReadImageAsPureCubicalComplex(file,n*30000);
> M:=PureComplexBoundary(M);;
> Add(L,M);
> od;;
gap> C:=L[1];;
gap> for n in [2..Length(L)] do C:=PureComplexUnion(C,L[n]); od;
gap> Display(C);
gap> Display(ContractedComplex(C));
