function setLog($log) {
		if (!$log) {
			$this->logFile = null;
			$this->logCallback = null;
		} elseif (is_callable($log)) {
			$this->logFile = null;
			$this->logCallback = $log;
		} else {
			Files::create($log);
			$this->logFile = $log;
			$this->logCallback = null;
		}
		return $this;
	}
function setLog($log) {
		if (!$log) {
			$this->logFile = null;
			$this->logCallback = null;
		} elseif (is_callable($log)) {
			$this->logFile = null;
			$this->logCallback = $log;
		} else {
			Files::create($log);
			$this->logFile = $log;
			$this->logCallback = null;
		}
		return $this;
	}
function setLog ( $ log ) { if ( ! $ log ) { $ this -> logFile = null ; $ this -> logCallback = null ; } elseif ( is_callable ( $ log ) ) { $ this -> logFile = null ; $ this -> logCallback = $ log ; } else { Files :: create ( $ log ) ; $ this -> logFile = $ log ; $ this -> logCallback = null ; } return $ this ; }
Sets logging for bussiness-logic level messages.

@param string|callback $log String filename or callback that forwards
messages to your own logging system.

@return Client
Sets logging for bussiness - logic level messages .