code: public function changeEncoding($encoding)
      {
          $encoding       = (string) $encoding;
          $this->string   = iconv($this->encoding, $encoding, $this->string);
          $this->encoding = $encoding;
  
          return $this;
      }
docs: Convert this sequence into another encoding.
  
  @param string $encoding The new encoding.
  
  @return StringBuilder