package main
 
import "fmt"
 
type TransformerFunction func(int) int
 
func NewCompositeTransformer(f, g TransformerFunction) TransformerFunction {
	return func(x int) int {
		return f(g(x))
	}
}
 
func Compose(f, g TransformerFunction, fs ...TransformerFunction) TransformerFunction {
	composite := NewCompositeTransformer(f, g)
 
	for _, f := range fs {
		composite = NewCompositeTransformer(composite, f)
	}
 
	return composite
}
 
func double(x int) int {
	return 2 * x
}
 
func inc(x int) int {
	return x + 1
}
 
func square(x int) int {
	return x * x
}
 
func main() {
	doubleThenIncThenSquare := Compose(square, inc, double)
	fmt.Println(doubleThenIncThenSquare(4))
}

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