code: public function addIndentation()
      {
          @trigger_error('The '.__METHOD__.' method is deprecated since version 1.27 and will be removed in 2.0. Use write(\'\') instead.', E_USER_DEPRECATED);
  
          $this->source .= str_repeat(' ', $this->indentation * 4);
  
          return $this;
      }
docs: Appends an indentation to the current PHP code after compilation.
  
  @return $this
  
  @deprecated since 1.27 (to be removed in 2.0).