Google Analytics Event function

function fireGaEvent(category, action, label, value)
{
    if (null === category) {
        category = 'Professional Learning';
    }
    if (ga) {
        if (value !== undefined && value !== '') {
            ga('send', 'event', category, action, label, value);
        } else {
            ga('send', 'event', category, action, label);
        }
    }
}