?

            例子：
class FileTool:
    def __init__(self, filepath):
        self.filepath = filepath

    def write_to_file(self, line):
        f = open(self.filepath, 'a')
        f.write(line)
        f.close()

    def read_to_file(self):
        f = open(self.filepath, 'r')
        lines = f.readlines()
        f.close()
        return lines