Аргументы по умолчанию равны "None" и если не записать одну то надо чтобы вместо "None" было просто пустой пробел

class Book:
    def __init__(self, title = None, author = None, edition = None):
        self.title = title
        self.author = author
        self.edition = edition

    def display(self):
        #a = self.edition
        #if filter(None.__ne__, a):
        #   a = ' '
        print("%-30s%-20s%5s" % ("Title", "Author", "Edition"))
        print('-'*58)
        print("%-30s%-20s%5s" % (self.title, self.author, self.edition ))

book = Book('Mobi-Dick', 'Melville', '1851')
book.display()