function _checkLayer($layer = null)
    {
        if (!empty($layer) && $layer != 'default') {
            $layers = $this->config->getLayers();
            if (!in_array($layer, $layers)) {
                return " only the layers: \"" . implode('" or "', $layers) . "\" are supported";
            }
        }

        return false;
    }
function _checkLayer($layer = null)
    {
        if (!empty($layer) && $layer != 'default') {
            $layers = $this->config->getLayers();
            if (!in_array($layer, $layers)) {
                return " only the layers: \"" . implode('" or "', $layers) . "\" are supported";
            }
        }

        return false;
    }
function _checkLayer ( $ layer = null ) { if ( ! empty ( $ layer ) && $ layer != 'default' ) { $ layers = $ this -> config -> getLayers ( ) ; if ( ! in_array ( $ layer , $ layers ) ) { return " only the layers: \"" . implode ( '" or "' , $ layers ) . "\" are supported" ; } } return false ; }
Checks if a layer is defined or not

@param string $layer The layer to search for
@return mixed False on no error or the error message
Checks if a layer is defined or not