static int calcOffset(CharSequence sequence, int startOffset, int column) {
    int i = 1;
    while (i < column) {
      int c = Character.codePointAt(sequence, startOffset);
      i += c == '\t' ? 8 : 1;
      startOffset++;
    }
    return startOffset;
  }
static int calcOffset(CharSequence sequence, int startOffset, int column)