public function parseFormula($formula) {
		//	Basic validation that this is indeed a formula
		//	We return an empty array if not
		$formula = trim($formula);
		if ((!isset($formula{0})) || ($formula{0} != '=')) return array();
		$formula = ltrim(substr($formula,1));
		if (!isset($formula{0})) return array();

		//	Parse the formula and return the token stack
		return $this->_parseFormula($formula);
	}