const pipeline = (...funcs) =>val => funcs.reduce((a, b) => b(a), val);const plus1 = a => a + 1;const mult2 = a => a * 2;const addThenMult = pipeline(plus1, mult2);addThenMult(5)我想下問 funcs.reduce((a, b) => b(a), val); 是什么意思pipeline(6,10) 之后是一個函數function reduce(){}里面是一個函數和一個數組作為參數嗎？？那個函數(a, b) => b(a), b(a)又是怎么理解呢？？？