text: import toInteger from "../toInteger/index.js";
  import toDate from "../../toDate/index.js";
  import requiredArgs from "../requiredArgs/index.js"; // This function will be a part of public API when UTC function will be implemented.
  // See issue: https://github.com/date-fns/date-fns/issues/376
  
  export default function startOfUTCWeek(dirtyDate, dirtyOptions) {
    requiredArgs(1, arguments);
    var options = dirtyOptions || {};
    var locale = options.locale;
    var localeWeekStartsOn = locale && locale.options && locale.options.weekStartsOn;
    var defaultWeekStartsOn = localeWeekStartsOn == null ? 0 : toInteger(localeWeekStartsOn);
    var weekStartsOn = options.weekStartsOn == null ? defaultWeekStartsOn : toInteger(options.weekStartsOn); // Test if weekStartsOn is between 0 and 6 _and_ is not NaN
  
    if (!(weekStartsOn >= 0 && weekStartsOn <= 6)) {
      throw new RangeError('weekStartsOn must be between 0 and 6 inclusively');
    }
  
    var date = toDate(dirtyDate);
    var day = date.getUTCDay();
    var diff = (day < weekStartsOn ? 7 : 0) + day - weekStartsOn;
    date.setUTCDate(date.getUTCDate() - diff);
    date.setUTCHours(0, 0, 0, 0);
    return date;
  }