code: public static Slice leftTrim(Slice utf8)
      {
          int length = utf8.length();
  
          int position = firstNonWhitespacePosition(utf8);
          return utf8.slice(position, length - position);
      }
docs: Removes all white space characters from the left side of the string.
  <p>
  Note: Invalid UTF-8 sequences are not trimmed.