docs: function (start, len) {
        if ('number' === typeof start) {
          if (start < 0 || start >= _emberMetalProperty_get.get(this, 'length')) {
            throw new _emberMetalError.default(OUT_OF_RANGE_EXCEPTION);
          }
  
          // fast case
          if (len === undefined) {
            len = 1;
          }
  
          this.replace(start, len, EMPTY);
        }
  
        return this;
      }