  if (str.length !== 64)
        return false;

    str = str.toLowerCase();

    var hexChars = '0123456789abcdef';
    for (var i = 0; i < str.length; i++) {
        if (hexChars.indexOf(str[i]) === -1) {
            return false;
        }
    }
    return true;
}

function $id(id) {
    return document.getElementById(id);
}

function $class(cl) {
    return document.getElementsByClassName(cl);
}

var wallet;

$id('returnKeyStart').addEventListener('click', function () {
    $id('import').value = null;
 