var entity = new IgeEntity();
entity.addGroup('g1', 'g2');
// Will output true since entity is part of g1 group
console.log(entity.inGroup('g1', false);
// Will output false since entity is not part of g3 group
console.log(entity.inGroup('g3', false);
var entity = new IgeEntity();
entity.addGroup('g1', 'g2');
// Will output true since entity is part of g1 group
console.log(entity.inGroup(['g1, 'g3'], false);
// Will output false since entity is not part of g3 group
console.log(entity.inGroup(['g1, 'g3'], true);