void fillRange(int start, int end, [E fill])

Sets the objects in the range start inclusive to end exclusive to the given fillValue.

An error occurs if start..end is not a valid range for this.

Source

void fillRange(int start, int end, [E fill]) {
  RangeError.checkValidRange(start, end, this.length);
  for (int i = start; i < end; i++) {
    this[i] = fill;
  }
}