repeat method
Implementation
String repeat([int n = 1]) {
if (n < 1) {
return '';
}
var result = '', string = this;
do {
if ((n % 2) > 0) {
result += string;
}
n = (n / 2).floor();
if (n > 0) {
string += string;
}
} while (n > 0);
return result;
}