python的类初始化

class book:
    _author=''
    _name=''
    _page=0
    price=0
    _press=''
    def _check(self,item):
        if item=='':
            return 0
        else:
            return 1

    def show(self):
        if self._check(self._author):
            print(self._author)
        else:
            print('No value')
        if self._check(self._name):
            print(self._name)
        else:
            print('No value')

    def setname(self,name):
        self._name=name
    def __init__(self,author,name):
        self._author=author
        self._name=name
       
a=book('Tom','A Wonderful Book')
a.show()