//Check whether a given value satisfies the Luhn Algorithm
is.validLuhn = function(value){
	var sum = 0, valuestr = value.toString().split("").reverse().join("");
    var luhnDigits = new Array();
    for(var i=0; i<valuestr.length; i++){

        if (i%2 != 0){

            console.log('Luhn Digit = '+valuestr.substr(i, 1));
            var luhnDigit = parseInt(valuestr.substr(i, 1))*2;
            if (luhnDigit>9){
                luhnDigitstr = luhnDigit.toString();
                luhnDigit = parseInt(luhnDigitstr.charAt(0)) + parseInt(luhnDigitstr.charAt(1));
            }

            luhnDigits.push(luhnDigit);

        }else{
            console.log('meh');
            luhnDigit = parseInt(valuestr.substr(i, 1));
        }
        if (i>0){
            sum += luhnDigit;
        }
    }
    console.log('Luhn Digits '+luhnDigits);

    console.log('Calculation sum '+sum);
    console.log('Verification Digit '+(sum*9)%10);
    console.log('Last Digit '+valuestr.substr(0, 1));
    var computedDigit = (sum*9)%10;

    return computedDigit.toString() == valuestr.substr(0, 1);
    console.log('Check digit = '+checkDigit);
}