// Flat
const array = ['ab', ['123', 13, [ 321 ], 123 ], 32123, 327]

function flat (array) {
    array.map(element => {
        if (element.isArray()) {
            flat()
        }
        return JSON.stringfy(element)
    })
}


// Invert String
function stringInvert (string) {
    const strArray = string.split('')
    const newArray = []
    for (let i = strArray.length; i > 0; i--) {
        newArray.push(strArray[i])
    }
    return newArray
}