function pipe(): void {
    $f1 = $a1 |> $b1;
    
    $f2 = $a2 |> $b2 |> $c2;
    
    $f3 = $a3 |> $b3 |> $c3 |> $d3;
    
    $f4 = f1(...) |> f2(...) |> f3(...);
}