original_string: public function create_directory($newdirname, $userid = NULL) {
          if (!$this->is_writable() or !$this->lf->is_directory()) {
              return null;
          }
  
          $newdirname = clean_param($newdirname, PARAM_FILE);
          if ($newdirname === '') {
              return null;
          }
  
          $filepath = $this->lf->get_filepath().'/'.$newdirname.'/';
  
          $fs = get_file_storage();
  
          if ($file = $fs->create_directory($this->lf->get_contextid(), $this->lf->get_component(), $this->lf->get_filearea(), $this->lf->get_itemid(), $filepath, $userid)) {
              return $this->browser->get_file_info($this->context, $this->lf->get_component(), $file->get_filearea(), $file->get_itemid(), $file->get_filepath(), $file->get_filename());
          }
          return null;
      }
code: public function create_directory($newdirname, $userid = NULL) {
          if (!$this->is_writable() or !$this->lf->is_directory()) {
              return null;
          }
  
          $newdirname = clean_param($newdirname, PARAM_FILE);
          if ($newdirname === '') {
              return null;
          }
  
          $filepath = $this->lf->get_filepath().'/'.$newdirname.'/';
  
          $fs = get_file_storage();
  
          if ($file = $fs->create_directory($this->lf->get_contextid(), $this->lf->get_component(), $this->lf->get_filearea(), $this->lf->get_itemid(), $filepath, $userid)) {
              return $this->browser->get_file_info($this->context, $this->lf->get_component(), $file->get_filearea(), $file->get_itemid(), $file->get_filepath(), $file->get_filename());
          }
          return null;
      }
code_tokens: public function create_directory ( $ newdirname , $ userid = NULL ) { if ( ! $ this -> is_writable ( ) or ! $ this -> lf -> is_directory ( ) ) { return null ; } $ newdirname = clean_param ( $ newdirname , PARAM_FILE ) ; if ( $ newdirname === '' ) { return null ; } $ filepath = $ this -> lf -> get_filepath ( ) . '/' . $ newdirname . '/' ; $ fs = get_file_storage ( ) ; if ( $ file = $ fs -> create_directory ( $ this -> lf -> get_contextid ( ) , $ this -> lf -> get_component ( ) , $ this -> lf -> get_filearea ( ) , $ this -> lf -> get_itemid ( ) , $ filepath , $ userid ) ) { return $ this -> browser -> get_file_info ( $ this -> context , $ this -> lf -> get_component ( ) , $ file -> get_filearea ( ) , $ file -> get_itemid ( ) , $ file -> get_filepath ( ) , $ file -> get_filename ( ) ) ; } return null ; }
docstring: Create new directory, may throw exception - make sure
  params are valid.
  
  @param string $newdirname name of new directory
  @param int $userid id of author, default $USER->id
  @return file_info|null new directory's file_info instance or null if failed
docstring_tokens: Create new directory may throw exception - make sure params are valid .