Explaination

higher-order-lamda.js

// If we wrote a multiply function:
const multiply = (n, m) => n * m
// If we wrote an expression:
[ 1, 2, 3, 4, 5 ].map( (m) => multiply(10, m) )
// It would evaluate to:
[ 10, 20, 30, 40, 50 ]

// But we could also write that example like:
const multBy = (n) => (m) => n * m
// And then if we wrote an expression:
[ 1, 2, 3, 4, 5 ].map( multBy(10) )
// Because multiply(10) returns a function It would still evaluate to:
[ 10, 20, 30, 40, 50 ]