def build_person(first_name, last_name, age=''):

    """返回一个字典，其中包含有关一个人的信息"""

    person = {'first': first_name, 'last': last_name}

    if age:

        person['age'] = age

    return person

person_1 = build_person('how', 'bin', '24')

person_2 = build_person('how2', 'bin2', '24')

persons = ['person_1', 'person_2']

for person in persons:

    myperson = {}

    exec("myperson = "+person)

    for key, value in myperson.items():

        print(key + ' ' + value)