static int getIndent(S s) {
  int n = Int.MAX_VALUE;
  for (line : linesIterator(s))
    line = rtrim(line);
    if (nempty(line)) {
      indent = getIndentOfLine();
      if (indent < n) {
        n = indent;
        if (n == 0) ret 0;
      }
    }
  }
  ret n;
}