执行下面Python代码后，输出的结果是？（    ）

users = [

{"name": "Tom", "skills": {"Python", "Java", "C++"}},

{"name": "Join", "skills": {"Python", "Java"}},

{"name": "Gaia", "skills": {"Java", "C++", "SQL"}}

]

skills_sets = (user['skills'] for user in users)

common_skills = set.intersection(*skills_sets) 

print(common_skills)