Some definitions of interest.
append	Def as @ bs == Case of as; nil  bs ; a.as'  [a / (as' @ bs)]  (recursive)
	Thm* T:Type, as,bs:T List. (as @ bs)  T List
compose_list	Def compose_list(L) == reduce(p,q. p o q;x.x;L)
	Thm* T:Type, L:(TT) List. compose_list(L)  TT
compose	Def (f o g)(x) == f(g(x))
	Thm* A,B,C:Type, f:(BC), g:(AB). f o g  AC

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