如何在python函数中定义字符串?

我读了一些教程却没有得到启发。有人能告诉我这里出了什么问题吗?

我还想知道如何在类中定义mytest1这样的东西,然后在函数中访问它?

from google.appengine.ext import webapp
from google.appengine.ext.webapp.util import run_wsgi_app

class MainPage(webapp.RequestHandler):
    #mytest1 = "test1" 
    #Runtime failure on this line talking about an indent issue
    def get(self, test = 'testing!'):
        mytest2= "test2" #Runtime failure on this line talking about an indent issue
        self.response.headers['Content-Type'] = 'text/plain'
        self.response.out.write('Hello, webapp World!\n')
        self.response.out.write(self)
        #self.response.out.write('\n' + mytest1)
        self.response.out.write('\n' + mytest2)

application = webapp.WSGIApplication(
                                 [('/', MainPage)],
                                 debug=True)

def main():
    run_wsgi_app(application)

if __name__ == "__main__":
    main()