/**
  * Returns the content of all cells as an associative array, indexed 
  * off the cell location  (ie 'A1', 'D4', etc).  Each element of 
  * the array is an associative array with a 'value' and a 'function'.  
  * Only non-empty cells are returned by default.  'range' is the 
  * value of the 'range' query parameter specified at:
  * http://code.google.com/apis/spreadsheets/reference.html#cells_Parameters
  *
  * @param string $range The range of cells to retrieve
  * @param boolean $empty Whether to retrieve empty cells
  * @return array An associative array of cells
  */
 public function getContentsAsCells($range = null, $empty = false)
 {
     $service = new Zend_Gdata_Spreadsheets($this->getHttpClient());
     return $service->getSpreadsheetCellFeedContents($this, $range, $empty);
 }