fn cascade(N:float,fb:float)->((float)->float){
	if(N>0.0) {
		|x:float| ->float { 
			(cascade(N-1.0,fb)(x)) *(1.0-fb) + self*fb
		}
	}else{
		|x:float| ->float {x}
	}
}
cascade(1.0,0.9)(1.2)