private function optDefaultArg($o) {
		$o = $this->opt($o);
		if (isset($this->spec[$o][4])) {
			return $this->spec[$o][4];
		}
		return null;
	}
private function optDefaultArg($o) {
		$o = $this->opt($o);
		if (isset($this->spec[$o][4])) {
			return $this->spec[$o][4];
		}
		return null;
	}
private function optDefaultArg ( $ o ) { $ o = $ this -> opt ( $ o ) ; if ( isset ( $ this -> spec [ $ o ] [ 4 ] ) ) { return $ this -> spec [ $ o ] [ 4 ] ; } return null ; }
Retreive the default argument of an option
@param string $o
@return mixed
Retreive the default argument of an option