lib/parse.js
function splitUnique (string) {
  string = string && string.trim();
  if (string) {
    return unique(string.split(/\s+/));
  } else {
    return undefined;
  }
}
function splitUnique (string) {
  string = string && string.trim();
  if (string) {
    return unique(string.split(/\s+/));
  } else {
    return undefined;
  }
}
splits a string on whitespaces and removes duplicate values