const genfun = require('./')
const { d } = genfun.formats

function multiply (a, b) {
 return a * b
}

function addAndMultiplyNumber (val) {
 const fn = genfun(`
 function (n) {
 if (typeof n !== 'number') {
 throw new Error('argument should be a number')
 }
 const result = multiply(${d(val)}, n + ${d(val)})
 return result
 }
 `)

 // use fn.toString() if you want to see the generated source

 return fn.toFunction({multiply})
}

const addAndMultiply2 = addAndMultiplyNumber(2)

console.log(addAndMultiply2.toString())
console.log('(3 + 2) * 2 =', addAndMultiply2(3))