src/utils.js
function normalizeEntity(entity) {
    if (entity !== null &&
            typeof entity !== 'undefined' &&
            typeof entity.getId === 'function') {
        return entity.getId();
    }
    return entity;
}
function normalizeEntity(entity) {
    if (entity !== null &&
            typeof entity !== 'undefined' &&
            typeof entity.getId === 'function') {
        return entity.getId();
    }
    return entity;
}
function normalizeEntity ( entity ) { if ( entity !== null && typeof entity !== 'undefined' && typeof entity . getId === 'function' ) { return entity . getId ( ) ; } return entity ; }
Normalizes `entity` to an id, where `entity` can be an id
or a Model instance.

@param  {*} entity - either a Model instance or an id value
@return {*} the id value of `entity`
Normalizes entity to an id where entity can be an id or a Model instance .