vendors/tempy.js/parseNegate/parseNegate
class parseNegate:    function parseNegate() {
      var pattern = this.pattern;
      var negate = false;
      var options = this.options;
      var negateOffset = 0;
      if (options.nonegate)
        return;
      for (var i = 0, l = pattern.length; i < l && pattern.charAt(i) === "!"; i++) {
        negate = !negate;
        negateOffset++;
      }
      if (negateOffset)
        this.pattern = pattern.substr(negateOffset);
      this.negate = negate;
    }